Quantum Frontiers issue of Physics World, March 2013

physicsworld.comVolume 26 No 3 March 2013Quantum frontiersPeering into an ever weirder world

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physicsworld.com Contents: March 2013iStockphoto/pixhookI Bloch, MPQRandom universe? – a quantum problem 29Ultracold atoms – quantum simulators 47–51On the coverQuantum frontiers: peering into an everweirder world 23–56(The Comic Stripper)physicsworldPhysics World is published monthly as 12 issues per annualvolume by IOP Publishing Ltd, Temple Circus, Temple Way,Bristol BS1 6HG, UKUnited States Postal Identification StatementPhysics World (ISSN 0953-8585) is published monthly byIOP Publishing Ltd, Temple Circus, Temple Way, BristolBS1 6HG, UK.Air freight and mailing in the USA by PublicationsExpediting, Inc., 200 Meacham Ave, Elmont NY 11003.Periodicals postage at Jamaica NY 11431.US Postmaster: send address changes to Physics World,IOP Publishing, PO Box 320, Congers, NY 10920-0320, USA.Quanta 3Frontiers 4Indistinguishable electrons ● Neutrons on demand ● How many dominoes wouldtopple a cathedral? ● Mobile networks map rainfall ● A double-helix archiveNews & Analysis 6Panel opts for RHIC closure ● NASA joins ESA dark-energy mission ● Chu resignsas US energy secretary ● Canadian astronaut joins quantum venture ● 71bn for10-year graphene project ● New institutes join online physics course ● Cumbriaditches nuclear-waste plan ● South Korea launches science satellite ● China unveils16 mega projects ● New lab for UK’s NPL ● Study finds evidence of duplicate grantsubmissions ● Croatia passes science reforms ● L’Aquila judge publishes verdictFeedback 19Letters about networking and the state of physics education in India, pluscomments from physicsworld.com on human hearingQuantum frontiersCritical Point 25The quantum moment Robert P CreaseForum 29Agreeing to disagree Maximilian SchlosshauerThe curious state of quantum physics 30Vlatko Vedral reminds us of the long-standing big unanswered questions aboutquantum physics and rounds up the latest developments in quantum researchIn praise of weakness 35A novel paradigm for studying the quantum world, known as weak measurement,has steadily been gaining hold over the last 20 years. Aephraim Steinberg, AmirFeizpour, Lee Rozema, Dylan Mahler and Alex Hayat outline its exciting potentialNature’s quantum subways 42Jim Al-Khalili reveals our latest understanding of DNA mutation on the molecularlevel, which looks to involve quantum tunnelling as a fundamental first stepQuantum leaps for simulation 47Immanuel Bloch describes how recent experiments with ultracold atoms bring uscloser to realizing Richard Feynman’s dream of a universal quantum simulatorThe quantum space race 52Quantum communication is set to enter space, as groups around the world pursuethe concept of a quantum satellite, write Thomas Jennewein and Brendon HigginsReviews 59Learn with Leonard Susskind ● Freeman Dyson’s iconoclastic career● Web life: The Quantum ExchangeGraduate Careers 67Soft landings: the skills you didn’t know you had● All the latest graduate vacancies and coursesRecruitment 81Lateral Thoughts 84The incomprehensibility principle Gordon FraserPhysics World March 2013 1

physicsworld.comQuantaFor the recordGraphene is just a bambinaUniversity of Manchester physicist Andre Geimquoted in the Financial TimesAlthough graphene is expected to transforma range of industries such as electronics,aerospace and energy, Geim says it could takeanother 40 years before the material makes itinto consumer products.Solving string theory won’t tell us howhumanity was bornHarvard University physicist Lisa Randallspeaking to New ScientistRandall admits to not thinking about a theory ofeverything when doing research, adding that theidea we will ever get one “is a bit challenging”.It is so distressing that even StephenHawking gets more attention for hisviews on space aliens than his viewson nuclear weaponsLawrence Krauss from Arizona State Universitywriting in the New York TimesKrauss warns that scientists’ voices are notbeing heard in debates over climate change andnuclear proliferation.I don’t want everything to be clear –I want to confuse people a little sothat they go away and read a bookUniversity of Manchester physicist Brian Coxquoted in the Daily TelegraphCox says that he tried to get more physics intohis new TV series – Wonders of Life – but theproduction team wanted the programme to beaccessible to a wider audience.Physics has been fortunate in recentyears to have benefited from giftedTV presenters, firing the beautyof the subject direct into people’sliving roomsPeter Knight, president of the Institute ofPhysics, quoted in the Daily TelegraphKnight says physics has benefited from its “geekchic”image, helped by the likes of Brian Cox.Each wheel has its own personalityCharlie Sobeck from NASA’s Ames ResearchCentre, quoted in New ScientistNASA put its Kepler mission on standby for10 days in January so that one of its “reactionwheels”, which control the probe’s motion alongan axis, could recover after being overworked.Seen and heardStars in their eyesHere is one little creature that didn’t makeit into our recent special issue on animalphysics. The dung beetle apparently usesboth the Sun and the Moon to orientateitself as it rolls its balls of muck along theground. But the big mystery in the dungbeetleworld was why the insect can stillnavigate when the Moon is absent fromthe night’s sky. Biologist Marie Dacke andcolleagues at the University of Lund inSweden have now shown that dung beetlesactually use the Milky Way to orientatethemselves. The researchers came to thissurprising conclusion after putting dungbeetles in the Johannesburg Planetariumin South Africa and then simulatingthe night sky, which showed that theinsects use the light from stars to movein a straight path. So is that dung beetlessorted then? Not quite. “They still offermany more riddles waiting to be solved,”Dacke reckons.Snow patrolYou might not think the World EconomicForum in Davos would have particlephysics high on its agenda, but it was thetalking point at this year’s annual shindigof political and business elites in the SwissAlps. Punters at Davos were particularlydrawn to CERN boss Rolf-Dieter Heuer’stalk about how the lab’s managementstructure could be applied to organizationssuch as the International Monetary Fundand the European Central Bank. “Theinternational realpolitik of Davos hasmore in common with the quantum worlds,where subatomic particles can occupydifferent sates simultaneously,” says AnneRichards, chief investment officer atAberdeen Asset Management who had athree-year spell as a CERN research fellowin the 1980s. However, the rarefied Alpineair probably went a bit to Heuer’s headas he offered this analogy of the Higgsboson to the Associated Press. “Supposethe Higgs boson is a special snowflake, soyou have to identify the snowflakes, in aEmily BairdiStockphoto/Elena Elisseevabig snowstorm, in front of a backgroundof snowfields,” he mused. “That is verydifficult. You need a tremendous amountof snowfall in order to identify thesnowflakes.” Maybe stick to those CERNmanagement structures, Rolf.The genius behind dark matterIt seems that US rapper GZA (also knownto his fans as The Genius) has takento physics. A founding member of hiphoplegends the Wu-Tang Clan, GZA isputting the finishing touches to his newalbum Dark Matter – a record he says ispartially inspired by quantum physics.GZA (real name Gary Grice) apparentlygot the idea for the album on a visit toHarvard University’s science centreand has even teamed up with ColumbiaUniversity education expert ChristopherEmdin to create “science genius battles” –a programme fusing hip-hop and scienceto help make physics more accessible tostudents. Get ready for a whole new waveof physics-based raps.More milk, more prizesFirst came the surprisingconclusion that chocolateconsumption can increasea nation’s chance ofproducing Nobel prizewinners (see January p3).Now Sarah Linthwaitefrom Gloucestershire Royal Hospitalin the UK claims that it is actually milkconsumption that is the key (Pract. Neurol.13 63). Linthwaite found what she saysis a positive correlation between milkconsumption and the number of Nobelprizes per capita. Sweden tops the list,getting through 340 kg of milk everyyear per person (and has the most Nobellaureates per capita) whereas Chinaonly consumes around 25 kg per personevery year (and has the fewest laureatesper head). “So to improve your chancesof winning Nobel prizes,” the authorsconclude, “you should not only eat morechocolate but perhaps drink milk too; orstrive for synergy with hot chocolate.”When two become oneAnd finally, we couldn’t resist bringingyou details of Destiny’s Child’s latestcompilation Love Songs, which includesthe new song “Nuclear”. “When the twobecome one on a quantum level,” Beyoncé,Kelly and Michelle sing, “it’s nuclear.With you here, we both heat up.” Maybe itshould have been a duet for Alice and Bob?Physics World March 2013 3

physicsworld.comFrontiersIn briefDiamond downsizes MRI and NMRMagnetic-resonance-imaging technologyhas been shrunk to the nanoscale by twoindependent teams of researchers in Germanyand the US, so that molecular samples just afew cubic nanometres in volume can now bedetected and imaged at room temperature. Bothgroups used nitrogen-vacancy (NV) defects indiamonds as magnetic-field sensors to probesuch minute samples. NV defects occur whentwo neighbouring carbon atoms in diamondsare replaced by a nitrogen atom and an emptylattice site. NV sites are capable of detecting thevery weak oscillatory magnetic fields that comefrom the spins of protons in a sample. Apartfrom being able to resolve a single atom at roomtemperature, the technique could be used as apolarizing agent for traditional NMR and couldalso help the nanotechnology community imagetiny devices (Science 339 557; 339 561).‘Just add water’ for hydrogen on demandSilicon nanoparticles could be used to producehydrogen almost instantly, as they react withwater, according to researchers in the US. Thereaction does not require any heat, light orelectricity and the hydrogen generated couldbe used to power small fuel cells. In essence,the technique recovers some of the energy thatgoes into refining the silicon and producing thenanoparticles in the first place. Thanks to theirhigh surface-to-volume ratio, the nanoparticlesshould naturally generate hydrogen much morequickly than bulk silicon. The advantage ofsilicon is that it is abundant on our planet, hasa high energy density and does not release anycarbon dioxide when it reacts with water. Theresearchers have already successfully testedtheir technique in a small fuel cell that they usedto power a fan (Nano Lett. 10.1021/nl304680w).Stored photons interact in atom cloudPhysicists in the UK have come up with anew way of storing a handful of photons in anultracold atomic gas, in which strong interactionsbetween neighbouring photons can be switchedon and off using microwaves. Once stored, thephotons can be made to interact strongly, beforebeing released again. An important feature ofthe technique is that it uses microwaves, whichare also used to control some types of stationaryqubit. The team believes that the techniquecould be used to create optical logic gates inwhich single photons could be processed one ata time. The method could also prove useful forconnecting quantum-computing devices basedon different technologies (arXiv:1207.6007v3).Read these articles in full and sign up for freee-mail news alerts at physicsworld.com4Emitting indistinguishable electronsemitter 1beam splitterA new method to produce indistinguishableand coherent electrons has been developedby scientists in France. They haveused it to make a small, electron-emittingchip that can produce two single electronsemitted from different sources that are inthe same quantum state. This is a key stepin developing electron-based quantuminformation-processingtechniques.Electrons are fermions and so must obeyPauli’s exclusion principle, which preventsidentical fermions from occupying thesame state, and so leads to anticorrelationsor “antibunching”. Erwann Bocquillon andGwendal Fève at the Ecole Normale Supérieurein Paris and Lyon, along with colleaguesfrom the Laboratory for Photonicsand Nanostructures, Paris, wanted to see ifindistinguishable electrons could be generatedby independent sources. But as thereare many electrons in any system, and theyall interfere with each other and with theenvironment, making coherent electronbeams is difficult.The researchers’ electron-emitting chipNeutrons on demandemitter 2Coherent beams A chip off the semiconductor dot.A new compact high-flux source of energeticneutrons has been built by physicistsin Germany and the US. The laser-baseddevice has the potential to be cheaper andmore convenient than the large neutronfacilities currently used by scientists andcould be housed in university laboratories.Built by Markus Roth of the TechnischeUniversität Darmstadt and colleagues atLos Alamos and Sandia national laboratories,the device builds on previous researchcarried out at Los Alamos in 2006, whichused computer simulations to show thatan intense laser beam can penetrate a thinsolid target, producing the necessary highenergyneutron flux. Roth’s team directedextremely powerful and well-definedpulses from the Los Alamos TRIDENTlaser onto a 400 nm-thick plastic targetD Darson(pictured) was built using a “very clean”micron-sized bulk-semiconductor samplein which the electrons propagate in straightlines for several microns in 2D before beingscattered, limiting their interactions. Astrong magnetic field is then used to furtherrestrict the movement of the electronsto only 1D so that single electrons may beguided to each of the emitters. By applying avoltage pulse to metallic electrodes depositedon top of the emitters, the researcherstrigger the emission of a single electron toan electronic beamsplitter that is made upof two input and two output arms. Fève saysthat their sample is capable of emitting billionsof single electrons per second – oneelectron per nanosecond.“The two sources are perfectly synchronizedsuch that both particles arrivesimultaneously on the splitter and perfectantibunching occurs, meaning the twoelectrons always exit in different outputs,”explains Fève. That means that the twoelectrons, generated by the two identical,synchronized emitters would arrive simultaneouslyat the two input arms of the splitterand would always emerge in two distinctoutputs, obeying Pauli’s principle.But Fève is quick to point out that whilethe team did achieve a high degree ofindistinguishability, some minimal environmentalinteraction did occur. Theteam is looking at making its sample evensmaller so that the electrons travel evenshorter distances, while keeping in mindthe effects of temperature at such sizes(Science 10.1126/science.1232572).doped with deuterium atoms that was positioned5 mm in front of a secondary targetmade from beryllium.Even though the pulses delivered lessthan a quarter of the energy employed inprevious experiments, they produced neutronsthat were nearly 10 times as energetic– up to 150 MeV – and nearly 10 times asnumerous. The group took the first radiographsusing this beam by placing a series oftungsten, steel and plastic objects betweenthe neutron source and a scintillating fibrearray that was linked to a CCD camera.Roth says that although his group’s deviceproduces fewer neutrons than reactors oraccelerators do, it packs the neutrons intopulses – each lasting just 10 –8 s. This makesit suitable for applications that need hightemporal resolution. Roth claims that, oncecommercialized, the entire device would fiton a lab bench and that only the target wouldneed shielding (Phys. Rev. Lett. 110 044802).Physics World March 2013

physicsworld.comFrontiersStephen Morris, University of TorontoHow many dominoes will topple a cathedral tower?When a science quiz on Dutch TV last year asked its participants how many dominoes would be needed to tipover a domino as tall as the Domtoren – a 112 m-tall cathedral tower in Utrecht – mathematical physicistJ M J van Leeuwen of Leiden University in the Netherlands got his thinking cap on. Starting with a standardsizeddomino 4.8 cm tall, he calculated the upper limit on how much larger each successive domino could bein this game of “domino multiplication”, suggesting that the maximum ratio of successive domino heights is30% larger than the widely accepted value of 1.5. Assuming a growth factor of 1.5, the answer is 20 dominoes,but pushing the growth factor to 2, it should easily be done with just 12. Inspired by Van Leeuwen’s research,the images above show Stephen Morris at the University of Toronto as he knocks over a series of 13 dominoeswith a growth factor of 1.5. He claims that the energy needed to tip the first fingernail-sized domino isamplified two billion times by the end of the chain reaction – when a 45 kg block crashes to the floor. “If I had29 dominoes,” says Morris, “the last domino would be as tall as the Empire State Building.” (arXiv:1301.0615)Mobiles map the rainCellular communication networks canbe used to accurately predict large-scalerainfall distribution patterns in real time,according to researchers in the Netherlands.The team created rainfall maps forthe whole of the country using data gatheredby telecom firms of the attenuationof microwave signals across 2400 networklinks over a four-month period. The resultingmaps are largely similar to measurementstaken by conventional weather-radarand rain-gauge techniques.The research was carried out by AartOvereem and colleagues from WageningenUniversity and the Royal NetherlandsMeteorological Institute. The team lookedat the minimum and maximum receivedsignal power at each telephone tower in anetwork over 15 min periods, as microwavesare sent from one tower to the next. Signalspassing through falling raindrops are partlyabsorbed by the water molecules and alsoget scattered slightly, lowering the powerthat reaches the receiving tower. The moreraindrops in the beam’s path – or the largerthe drops are – the more signal power is lost.By comparing received powers foreach network link with reference valuesfor known dry periods – and factoringin humidity and the water films that candevelop on the communications antennae– the researchers were able to calculate therainfall densities along each path. Thesevalues were then treated as point measurementsat the centre of each network link andused to extrapolate the larger rain-distributionmaps. In the frequencies employedin these links, attenuation caused by raindropsare the only main source of powerreductions, apart from free space losses(PNAS 10.1073/pnas.1217961110).InnovationDigital files stored andretrieved using DNAScientists in the UK have stored about amegabyte’s worth of text, images and speech intoa speck of DNA and then retrieved that data backalmost faultlessly. The research was carried outby Nick Goldman and colleagues at the EuropeanBioinformatics Institute, who have stored digitalinformation by encoding it in the four differentbases that make up DNA. While the techniquedoes not offer the convenience of randomaccess or being rewriteable, its advantagesinclude being highly durable and also offering anextremely high-density storage method.The group used DNA that was produced in thelab rather than from living organisms, since thelatter is vulnerable to mutation and data loss.Unfortunately, it is only possible to synthesizeDNA in short strings and the shorter a string is,the lower its data storage capacity. So the teamdevised a coding scheme in which a fraction ofeach string is reserved for indexing purposes,specifying which file the string belongs to andat what point in the file it is located, allowing asingle file to be made up of many strings.To avoid errors that occur during both writingand reading the team encoded data in trits –digits with the values 0, 1 or 2 – and stipulatedthat a given trit is represented by one of thethree bases not used to code the trit immediatelypreceding it. The researchers tested theirscheme by encoding five data files into singleDNA sequences and then split those sequencesup into roughly 150 000 individual strings, all117 bases long. They encoded a PDF of Watsonand Crick’s famous double-helix paper, aShakespearian sonnet and an audio recordingof 30 s of Martin Luther King’s “I have a dream”speech in MP3 format. The team then uploadedthe encoded files to a private webpage to enablea company in California to synthesize the DNA.The DNA was then sent as a tiny quantityof powder at room temperature and withoutspecialized packaging to the European MolecularBiology Laboratory in Germany, where all fivefiles were sequenced and decoded. Four of thefiles were identical copies of the originals, whilethe fifth required some minor adjustment torecover its full set of data.The researchers claim to have achieved adensity of 2 petabytes per gram of DNA, whichcould, in principle, allow at least 100 millionhours of high-definition video to be stored in ateacup. Currently the technology is too expensiveto be competitive for all but the most long-termarchiving, but Goldman is confident that priceswill come down (Nature 494 77).Physics World March 2013 5

physicsworld.comNews & AnalysisNuclear physics faces loss of colliderA government panel in the US has recommended the closure of the hugely successful RelativisticHeavy Ion Collider at Brookhaven National Laboratory if funding for nuclear physics is not increased,as Peter Gwynne reportsThe budgetary shortfalls that havegripped the US over the past yearseem ready to claim a new victim:the nuclear-physics programme. Areport released early last month,by a subpanel of the government’sNuclear Science Advisory Committee(NSAC) concluded that thecountry will have to close one of itsthree large nuclear-science facilitiesunless the field receives at least asmall increase in government funding.It opted for the axe to fall onperhaps the best known facility –the Relativistic Heavy Ion Collider(RHIC) at Brookhaven NationalLaboratory in New York.The report had been commissionedlast April by William Brinkman,head of the Office of Scienceat the Department of Energy (DOE)in response to indications that loomingausterity could freeze the department’s$547m annual budget fornuclear physics. The panel chargedwith writing the report – led bynuclear physicist Robert Tribble ofTexas A&M University – consideredthree budget scenarios for thenext five years: zero growth, annualgrowth at a level similar to inflation,as well as a “modest increase” of1.6% annually above inflation.Only under the last scenario, thepanel concluded, could the countryoperate all three of its majornuclear-physics facilities. In additionto the 13-year-old RHIC, theseare the Continuous Electron BeamAccelerator Facility (CEBAF) at theThomas Jefferson National AcceleratorFacility in Virginia, which isundergoing a $310m upgrade, andthe $615m Facility for Rare IsotopeBeams (FRIB) under construction atMichigan State University (see box).The panel concluded that CEBAFshould be maintained “under allbudget scenarios”, owing to theamount already invested in it, whichincluded $65m from the 2009 AmericanRecovery and Reinvestment Act.But choosing which of the other two6to sacrifice proved difficult. “If weclose the RHIC now, we cede allcollider leadership – and not justthe high-energy collider – to CERNand we lose the scientific discoveriesthat are enabled by the recentintensity and detector upgrades atthe RHIC,” the report notes. “If weterminate FRIB construction, futureleadership in the cornerstone area ofnuclear structure and nuclear astrophysicswill be ceded to Europe andAsia. In addition a window of opportunityto construct the FRIB withsignificant non-federal resourcespledged to the project will close andis not likely to reopen.”Close callThe panel finally opted to recommendclosing RHIC, which has anannual budget of $160m, but admittedthat “losing any one of the componentswill cause severe and lastingdamage to the field”. Tribble latertold Physics World that the vote was“very close”, although the committeedecided not to publicly reveal theactual count. The US nuclear-physicscommunity responded swiftly to thereport by vowing to fight for a budgetTesting timesBrookhaven NationalLaboratory’sRelativistic HeavyIon Collider may haveto close if funding forthe US Departmentof Energy is cut.Brookhaven National Laboratoryincrease, which Tribble himself willsupport. “I will do whatever I canto help in that regard,” he says. “Allpanel members feel very stronglythat this could be a serious problemfor US nuclear physics.”Even before the report wasreleased, the heads of the threefacilities had begun collaborativeefforts to counter the potentialloss of a major facility. “We allappreciate that our general bestinterests are served by a differentoutcome than the cut,” says DoonGibbs, Brookhaven’s interim director.Meanwhile, Robert McKe own,deputy director for science at the Jeffersonlab, admits to being “relieved”that his is not the facility likely to bein jeopardy but adds that “losingany one of our facilities would be avery devastating blow to the field”.Similarly, Konrad Gelbke, directorof the National SuperconductingCyclotron Laboratory at MichiganState, which is overseeing planningfor the FRIB, points out “huge lossesto research in nuclear physics if themore stringent budget scenario isplayed out”.Fighting onLeaders of the nuclear-physics community,however, emphasize thatthe DOE and the government donot have to accept the panel’s recommendations.Indeed, Congresshas not even determined a budgetfor the DOE for the current financialyear. The heads of all threefacilities, along with members of thenuclear-physics community and scientificsocieties such as the AmericanPhysical Society, have alreadybegun a powerful effort to persuadelocal representatives, senators andCongress as a whole that US sciencewill suffer in both the short and thelong term without a small increase inthe nuclear physics budget.The message has certainly reachedleaders at the DOE. “None of thisbodes well for science at the ratePhysics World March 2013

physicsworld.comNews & AnalysisDifferent but related: the three US facilities battling for survivalThe three major US nuclear-physicsfacilities under threat by budgetdifficulties – Brookhaven NationalLaboratory’s Relativistic Heavy IonCollider (RHIC), the Continuous ElectronBeam Accelerator Facility (CEBAF) at theThomas Jefferson National AcceleratorFacility and the Facility for Rare IsotopeBeams (FRIB) under construction atMichigan State University – have differentbut related goals and technologies.The RHIC is primarily designed tostudy the “phase diagram” of nuclearmatter from almost baryon-free matter attemperatures up to four trillion degreeskelvin down to baryon-dense matter atlower temperatures. “It is by far the mostpowerful in the world in terms of intensityand most versatile in terms of energy,” says Brookhaven’s associate directorBerndt Müller. Those capabilities stem largely from a series of upgradesover the past decade that have increased the collider’s luminosity and theprecision of its detectors. “The RHIC we have now is a new machine in manyrespects – in its ability to accelerate uranium to the detectors – with almostno resemblance to 10 years ago, covering science that was not envisionedStill running CEBAF at Jefferson Lab currently seems to be safe.when it was constructed,” adds Müller.Recent discoveries include a new form ofmatter – a strongly coupled quark–gluonplasma – that was created by collisions ofgold ions.As for the FRIB, it will be complete in2021 and be based on a high-poweredsuperconducting linear accelerator thatwill be able to produce rare isotopes. TheFRIB will be the world’s most powerfulradioactive beam facility, able to makenearly 80% of the isotopes predicted toexist for elements up to uranium.CEBAF, meanwhile, will provide a highintensitycontinuous beam of electronsusing superconducting radio-frequencytechnology. The facility is currentlyundergoing a long shutdown as part of theupgrade that will double the accelerator’s energy from 6 GeV to 12 GeV, withthe goal of starting its new science programme in 2015. The electron beamin the upgraded facility can be split and delivered simultaneously to threedifferent experimental halls. According to Robert McKeown, deputy directorfor science at the Jefferson lab, one of these halls will feature a “flagshipexperiment” that will use a 9 GeV photon beam to search for exotic mesons.Thomas Jefferson National Accelerator Facilitywe’re going here,” Brinkman told thesubpanel in Washington at a hearing,adding that it “represents permanentdamage to the field”. But if Congressand the Obama administration failto avoid the looming budget cutsin the “financial sequester” – theagreement to reduce governmentspending across the board if the twosides cannot agree on a budget – thenthe cuts look more of a reality. “Wedidn’t spend much time on sequestration,”says Tribble. “If it occurs,it will be such a problem in all partsof government that it’s impossibleto know what the impact will be onnuclear physics.”One concern is that the sequestercould lead to a ban on starting anynew programmes at all. That couldaffect the FRIB, which has not yetreceived the necessary “critical decision2” go-ahead from the DOE.Even if that situation does not occur,the field could lose so much financialsupport that it might even have toclose two machines rather than one.SpaceNASA joins Europe’s dark-energy missionNASA has signed an agreementwith the European Space Agency(ESA) to collaborate on a space missionto study dark matter and darkenergy. ESA’s $800m Euclid missionis expected to launch in 2020 andwill spend six years measuring andmapping around two billion galaxiescovering more than one-third of thesky. NASA is now expected to providearound $100m towards the constructionof the probe, with the spaceagency’s involvement likely to extendthe science that can be achieved.Dark energy, which makes uparound 73% of the universe, isbelieved to be the driving forcebehind the universe’s expansion butis a substance about which we havealmost no knowledge. Dark matter,meanwhile, accounts for a further23% of the universe, with the restHelping handsNASA is expected toprovide around$100m towards theEuropean SpaceAgency’s $800mEuclid mission,which will study darkenergy and darkmatterESA/C Carreaubeing ordinary visible matter. “Thestudy of dark energy was identifiedas an important scientific questionin the 2010 Decadal Survey ofAstrophysics by the National Academiesof Science,” NASA spokesmanJames Harrington told PhysicsWorld. “Euclid will make significantprogress in understanding thenature of it.”Euclid will be armed with twostate-of-the-art instruments – anoptical visual imager and a nearinfraredspectrometer. For theinfrared instrument NASA will nowbe providing 16 detectors, plus fourspares, to the tune of $50m. NASAwill be giving a further $50m to supportthe 54 US scientists who willnow be joining the mission, the bulkfrom the Jet Propulsion Laboratoryin Pasadena, California. “By providingUS-made detectors for themission and by having US scientistsworking on the mission, both theEuropean and US science communitieswill benefit,” says Harrington.This is not the first time thatNASA and ESA have workedtogether on a major mission, havingcollaborated on the Hubble andJames Webb space telescopes as wellas on the Cassini and Huygens missionsto Saturn and the Herschel andPlanck observatories. “We welcomeNASA’s contribution to this importantendeavour, the most recent in along history of co-operation in spacescience between our two agencies,”says Álvaro Giménez, ESA’s directorof science and robotic exploration.NASA says it hopes the experienceit gains on Euclid will help it withthe construction of the Wide-FieldInfrared Survey Telescope mission,which is planned for launch in thecoming decade to study dark energyand dark matter.Gemma LavenderPhysics World March 2013 7

News & Analysisphysicsworld.comPeopleSteven Chu steps down as US energy secretaryThe Nobel laureate Steven Chu hasannounced he is to resign as USenergy secretary. When Chu departs,which as Physics World went to presswas expected to be by the end of February,he will have served in the postfor four years – longer than any of the14 previous heads of the Departmentof Energy (DOE). Chu now plans toreturn to “an academic life of teachingand research” in California.Politically independent, Chureceived plaudits from Democratsand environmentalists during histime as energy boss, which spannedthe whole of President Barack Obama’sfirst term in office beginningin 2008. “Steve helped my administrationmove America towardsreal energy independence,” Obamasaid in a statement. “Over the pastfour years we have doubled the useof renewable energy, reduced ourdependence on foreign oil and putour country on a path to win theglobal race for clean-energy jobs.”In a letter to DOE staff, Chu notedhis successes in office, such as fundingthe Advanced Research ProjectsAgency–Energy – a programmeto promote and fund research anddevelopment in novel energy technologies.The agency’s work inareas such as improving batteriesfor electric vehicles and developingmanufacturing technologies forsolar cells has drawn plaudits acrossthe board, as did his “SunShot initiative”– an effort to increase US useof renewable-energy technologies –that began progress towards a goal ofreducing the cost of solar power to $1per watt. “Secretary Chu has led theenergy department at a time whenour nation made the single largestinvestment ever in clean energyand doubled its use of renewables,”stated Gene Karpinski, president ofthe League of Conservation Voters.Yet Chu also became a controversialfigure, facing heavy criticismfrom Republicans, deniers of climatechange and some members of thebusiness community. Critics focusedon occasional failures of Chu’s initiatives,such as Solyndra – a solar-cellmanufacturer that went bankruptafter receiving $535m in DOE loanBack to EarthCanadian astronautSteve MacLean hasresigned aspresident of theCanadian SpaceAgency to beinvolved in a newquantum-physicsventure in Waterloo.Back to the labNobel laureateSteven Chu says thathe will now return to“an academic life ofteaching andresearch” inCalifornia.a spokesperson from the PerimeterInstitute declined to give any. In astatement the institute said only that itwas “very pleased that the innovationand technology cluster in the Waterlooregion has attracted someone of SteveMacLean’s calibre” and that it lookedforward “to collaborating with him andother partners who are building thequantum valley”.Information on MacLean’s planswas also scarce at the University ofWaterloo, which is home to the new$100m (C$160m) Mike and OpheliaLazaridis Quantum-Nano Centre thatwas opened by Stephen Hawking lastyear, as well as at Communitech,a Waterloo-based hub that aims tocommercialize technologies. Bothguarantees – as well as A-123 Systems,an innovative battery makerthat went bust before being rescuedby a Chinese conglomerate.Daniel Kish, senior vice-presidentof the Institute for Energy Research,a Washington DC-based non-profitcorporation, asserted that the emphasison renewables has cost jobs. “Thepolicies and priorities of Chu’s energydepartment have benefited ourglobal competitors and intensifiedthe economic pain felt by millionsof unemployed Americans,” he says.Chu responded to those criticisms inhis letter to DOE’s employees. “Thetruth is that only 1% of the companieswe funded went bankrupt,” he noted.“The test for America’s policymakerswill be whether they arewilling to accept a few failures inexchange for many successes.”The Obama administration willnow nominate a successor, with theDemocrat politicians Bill Ritter ofColorado, Jennifer Granholm ofMichigan and Christine Gregoire ofWashington state as top favourites.Yet there is a possibility that Chu’ssuccessor will be another scientist:theoretical physicist Ernest Monizof the Massachusetts Institute ofTechnology, who served as undersecretaryof energy for former USpresident Bill Clinton.Peter GwynneBoston, MAQuantum physicsPlans for departing Canadian space chief kept under wrapsThe head of the Canadian Space Agency(CSA), Steve MacLean, quit as presidentlast month after revealing he is planningto join a new quantum-physics venture inWaterloo. The venture will be led by MikeLazaridis, who co-founded ResearchIn Motion – the company behind theBlackBerry smartphone – and later setup the prestigious Perimeter Institutefor Theoretical Physics, also in Waterloo.Although details of the initiativeare being kept under tight wraps, it isknown that the new joint effort betweenLazaridis and MacLean will be separatefrom the Perimeter Institute’s activities,which focus on areas such as quantumgravity, quantum information andquantum fundamentals. But when askedfor more details on MacLean’s plans,NASA/JSCDOEinstitutions told Physics World they hadno knowledge of the new initiative, whileMacLean himself did not respond to aninterview request.MacLean received a BSc in physics in1977 and a PhD in physics in 1983 fromYork University in Toronto. That year hewas also selected as one of the firstsix Canadian astronauts, going on twomissions to space in 1992 and 2006. Onthe 1992 flight MacLean tested a laservisionsystem, a predecessor to roboticarms such as the Canadarm2 that iscurrently used on the InternationalSpace Station to capture spacecraft. In2008 he was named CSA president for afive-year term.Elizabeth HowellToronto8Physics World March 2013

physicsworld.comNews & AnalysisFundingEurope backs graphene research with €1bn boostThin futureThe 10-yeargraphene project willlead to thedevelopment of newtechniques for thefabrication ofgraphenenanodevices as wellas the integration ofgraphene-basedopto-electronicdevices.A project to commercialize graphenehas been awarded 71bn overa 10-year period by the EuropeanCommission (EC). Led by theoreticalphysicist Jari Kinaret of ChalmersUniversity of Technology inSweden, the graphene project beatoff four other bids for one of twohuge new 71bn Future and EmergingTechnologies awards – the otherwinning project being on brainresearch. The graphene projectinvolves 126 academic and industrialresearch groups from 17 EU memberstates and will consist of 15 “packages”,each representing a differentapplication area of graphene and ledby a different expert.Half of the funding will come fromthe EC’s Horizon 2020 programme,which promotes research and innovationin the EU, with the otherhalf coming from national budgetsor industry. The graphene projectwas awarded the money after gainingwide support – particularly fromNeelie Kroes, the EU commissionerfor digital agenda. She says the projectwill help create a European “graphenevalley” that will connect theacademic and industrial consortium.Only the first 30 months of the programmehave detailed goals at themoment. These include the developmentof different techniques formaking graphene nanodevices, thedesign of a graphene-based receiverunit for radio signal processing andthe integration of a graphene-basedopto-electronic and nano-photonicdevice. However, Kinaret is notconcerned about the lack of targetsover the whole of the 10-year project.“We are doing research, not development,”says Kinaret, “and a definingfeature of research is uncertainty.”Kinaret insists, though, that the projectdoes have a number of detailedEducationOnline-learning provider edX doubles membershipA major digital education initiativeset up by Harvard University and theMassachusetts Institute of Technology(MIT) has just doubled its numberof university partners and signedup its first members from outsidethe US. The edX programme, whichoffers free online learning, is nowjoined by universities in Canada,Australia, the Netherlands andSwitzerland. “We have had an internationalstudent community almostfrom the beginning and bringingthese leading international universitiesinto edX will help us meet thetremendous demand we are experiencing,”says edX president AnantAgarwal from MIT.edX is a not-for-profit educationprogramme offering “MOOCs”,or massive open online courses.MOOCs differ from conventionalonline learning programmes,being free of charge, offering vastresources and not usually leadingto any formal credit being awardedby the providers. Although MOOCshave existed for several years, thefounders of edX say they are raisingthe bar by building an entire opensourceplatform that links some ofthe world’s leading universities. Atypical edX course consists of “learningsequences” involving videospresented by university academics,along with assessments and onlineinteractive laboratories.Harvard and MIT both invested$30m in edX early last year and weresubsequently joined in the initiativeby the University of California atBerkeley, the University of Texas,Wellesley College and GeorgetownUniversity. Now, these six institutionswill be joined by Rice University(also in the US), McGill andToronto universities in Canada, plusthe Australian National University,Watch and learnAnant Agarwal,president of edX, hasgiven an exclusivevideo interview toPhysics World, whichcan be viewed onlineand in our digitalissue.long-term goals, for example in electronics,optics, energy applicationsand composite materials.Andre Geim from the Universityof Manchester, who shared the 2011Nobel Prize for Physics with his colleagueKonstantin Novoselov fortheir work on graphene, says thatwith so many potential technologiesthat have already been suggested forgraphene, the chances are “sky high”the project will deliver something.“Graphene is my best bet for the nextbig technological breakthrough,”says Geim. “Nevertheless, one needsto remember that it takes typically40 years for a new material to movefrom academia to consumer shelves.Graphene progresses unbelievablyfast, having reached industrial labsalready, but our expectation shouldremain realistic.”News of the 71bn European awardfor graphene came just weeks aftera report by the intellectual-propertyconsultancy CambridgeIP noted thatthe US and Asia currently hold thelion’s share of graphene patents, withKorean electronics giant Samsungalone filing more than 400.Senne StarckxMol, BelgiumDelft University of Technology inthe Netherlands, and the École PolytechniqueFédérale de Lausanne inSwitzerland. “Each of these schoolswas carefully selected for the distinctexpertise and regional influencethey bring to our growing family ofedX institutions,” says Agarwal.All six current edX memberslaunched courses in 2012 and havenew courses starting this spring.Among the new batch is a courseon electricity and magnetism taughtby Walter Lewin, an MIT physicistwho already has a strong online followingthrough earlier recordedlectures. Other existing edX coursesinclude those on quantum mechanicsand computing taught by Berkeleyacademic Umesh Vazirani,and on solid-state chemistry byMIT human-genome pioneer EricLander. According to edX spokespersonDan O’Connell, Delft hasalready indicated that it will be beginoffering edX courses from autumn,including courses on solar energyand space engineering.James DaceyPhysics World March 2013 9iStockphoto/nobeastsofierce

physicsworld.comNews & AnalysisUKCumbria rejects hosting nuclear-waste repositoryThe UK government will have tolook elsewhere to store its mountingnuclear waste after plans wererejected to assess sites in Cumbriafor a £12bn underground nuclearwasterepository. On 30 Januaryseven of the 10 members of CumbriaCounty Council cabinet votedagainst a proposal to build an undergroundlaboratory in the region thatwould have acted as a testbed for afull-scale storage. District councilsin west Cumbria are now hoping thatthe veto – the second in 14 years –will be overruled by the government.The UK has been generatingnuclear waste since its first nuclearpower station fired up in 1956. Sincethen the country has accumulatedsome 470 000 m 3 of waste, whichcould remain dangerously radioactivefor up to a million years. Mostof the high- and intermediate-levelwaste is currently in temporaryabove-ground storage at the Sellafieldnuclear- reprocessing site inwest Cumbria. The UK government,however, would like to find apermanent place to store the wastebecause of fears that the storage atSellafield is deteriorating. Indeed,last year the UK’s National AuditOffice reported that Sellafield’sstorage posed an “intolerable risk”to people and the environment.Cumbria has been seen as a possiblesite to permanently store theRisk concernsCumbria in the UK isalready home to theSellafield nuclearreprocessing site,which closelymonitors itsenvironmentalimpact, but now theregion’s council hasrejected a proposed£12bn undergroundnuclear-wasterepository.Space scienceSatellite sets path for South Korean space missionsSouth Korea has succeeded in launchinga satellite into orbit after months ofdelays and following two failed attemptsin 2009 and 2010. The probe – dubbedthe Science and Technology Satellite2C (STSAT-2C) – took off at the end ofJanuary from the Naro Space Center,located around 480 km south of Seoul.Scientific payloads aboard the probeinclude an instrument to monitorradiation levels as well as an altimeterto provide precise information about thesatellite’s orbit.Shortly after lift-off, the Koreanministry of education, science andtechnology announced that STSAT-2Chad successfully deployed in a low-Earthorbit, while contact with ground stationswas made 11 hours later, confirmingthe target orbit of 297 km by 1512 km.“[The rocket] proved that Korea hasthe ability to launch a space vehicle.This space technology representsthe [high] standard of our country’sscience and technology,” Yeong HakKim, a government official at the Koreanministry of education, science andtechnology, told Physics World.The probe was launched by Korea’sSpace Launch Vehicle (KSLV-1), alsoknown as Naro, which is a two-stagecarrier rocket that, when fully loaded,stands 33 m tall and has a mass ofaround 140 000 kg. The first stage of thelaunch vehicle was designed and builtby Russia’s Khrunichev State Researchand Production Space Center, whilethe second stage was developed by theThe project is ademonstrationof SouthKorea’sgrowing spaceprowesswaste underground at depths ofup to 1 km because of the existingnuclear facilities at Sellafield. However,some geoscientists are opposedto underground storage in the regionbecause it is thought to containunstable geology such as rock fractures,which can allow the spread ofwaste-leeching groundwater. Thereare also concerns that undergroundwaste would threaten tourism at thenearby Lake District National Park.Stuart Haszeldine, a geoscientistat the University of Edinburgh whohas investigated Cumbria’s suitabilityfor underground nuclear-wastestorage, told Physics World that hewas pleased with the outcome. “Itwas quite unexpected to win,” hesays. “I didn’t think Cumbria CountyCouncil would have such good judgement.”Haszeldine believes thatother parts of the UK would be moregeologically suitable for the constructionof an underground storagefacility, such as around the defunctnuclear power station in Oldbury,near Bristol.Many, however, are frustrated bythe vote’s outcome. UK energy secretaryEdward Davey says it was “disappointing”,adding that the decisionwill “not undermine prospectsfor new nuclear power stations”.Meanwhile, council leaders fromCopeland – the district that hostsSellafield – and from neighbouringAllerdale have written to the governmentto ask if there is still a way thatwest Cumbria can be considered forlong-term nuclear-waste storage.Councillor Elaine Woodburn ofCopeland told Physics World thatmore than two-thirds of Copelandresidents wanted to see west Cumbriareconsidered, and that somegeological experts would like to seea more detailed investigation. “Theimpact of hosting over 70% of thiscountry’s waste is felt economically,environmentally and socially,” saysWoodburn. “Whether it stays orgoes, it affects us, so we need to bepart of the solution. Whether [that]solution is in Copeland, I don’t know;we don’t have the facts to allow thatdecision to be taken.”Jon CartwrightKorea Aerospace Research Institute.The immediate scientific value ofthe satellite will be relatively smallwith the project being more of ademonstration of South Korea’s growingspace prowess. Indeed, North Korea’sapparent success in launching a longrangerocket in January put pressureon Seoul to ensure that KSLV-1’s spaceflight went to plan. Both countries onthe Korean peninsula are now membersof the exclusive group of 11 nations thathave independently launched satellitesfrom their own territory. However, SouthKorea will still have to make significantprogress before comparisons can bedrawn with other space-faring nationssuch as China and Japan.Toby BrownPhysics World March 2013 11Sellafield Ltd

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physicsworld.comNews & AnalysisAsiaChina signs off big science infrastructure planChina’s state council has approveda major infrastructure constructionprogramme for science and technologyover the coming two decades.Running from 2012 to 2030,the programme will aim to boostinnovation in China, support majorscientific breakthroughs and speedup construction of major scientificfacilities. Seven areas that focuson China’s strategic aims are earmarked,including energy and materialsresearch, Earth systems andenvironments, as well as particle andnuclear physics.The programme will see Chinabuilding some 16 major projects,which include establishing a seafloorobservatory network and carryingout a precise survey of China’sresources by measuring the strengthof gravity at varying locationsaround the country, the latter beingled by Huazhong University of Scienceand Technology and the ChineseAcademy of Sciences. The statecouncil maintains that, rather thanjust being run by leading universitiesand institutions, all the projectsshould involve better collaborationand the results be openly shared.Physicists in China have broadlywelcomed the plan. “It focuses onThe National Physical Laboratory(NPL) in Teddington, UK, is toreceive £25m towards the constructionof an Advanced MetrologyLaboratory (AML) that will containup to 20 labs and be complete by2017. The AML will be housed in anew building on the NPL site, withresearch focusing on areas such asgraphene, nano-analysis and timeand frequency measurements.“The key feature of the new laboratoryis the stable, high-specificationenvironment it will provide,[such as] low magnetic field andvibration, and very stable temperatureand humidity control,” says BillNimmo, a senior research scientist atNPL. It is also hoped that the AMLwill foster stronger links betweenNPL and academia. “This arrangementwill attract industry partnersand funding from multiple sources,”adds Nimmo.The plan givesa high level ofconfidence inChina’s abilityto innovatecutting-edge research for the sevenfields so this is an important plan forChina,” says astrophysicist Tipei Lifrom Tsinghua University and theInstitute of High Energy Physics inBeijing. “While many other countries’research budgets are decreasing,China’s budget is increasing.”Mi Xu, a senior adviser for thefast-reactor programme based at theChina Institute of Atomic Energy inBeijing, agrees with the plan’s aims.“It has given me a high level of confidencein China’s ability to independentlyinnovate,” he told PhysicsWorld, pointing to how the countryhas already led the way in buildinga fast-neutron reactor – one that can“breed” its own fuel – located in theFangshan District on the outskirts ofBeijing (see September 2011 p9).Meanwhile, the state council meetingin January also amended fourregulations regarding the enforcementof copyright law and the protectionof computer software. Thechanges were made in an attempt tointensify a crackdown on intellectualcopyright infringement and combatthe manufacture and sale of counterfeitproducts.Jiao LiBeijingUKNPL scoops £25m for advanced metrology centreBigger and betterThe NationalPhysical Laboratoryin Teddington, UK,will build anAdvanced MetrologyLaboratory todevelop improvedtime and frequencystandards.NPLCash for the AML is part of aUK government initiative to targetinvestment in eight so-called “greatscience areas” – for which £460mhas been allocated from a total£600m fund, originally announcedlast year. Other areas include £189mfor big data and energy-efficientcomputing, £45m for new facilitiesand equipment for advanced materialsresearch, as well as £50m forupgrades to research equipmentand laboratories.Kulvinder Singh ChadhaSidebandsNSF director quitsMaterials scientist Subra Suresh hasannounced his resignation as directorof the US National Science Foundation(NSF). In a letter to staff he said he wouldbe leaving at the end of this month tobecome president of Carnegie MellonUniversity. Suresh, a former dean of theMassachusetts Institute of Technology,was appointed NSF director in October2010 for a six-year period. In the letterhe said it has been an “extraordinaryhonour” to lead the NSF, which hasa budget of around $7bn. “Despitethe economic crisis and the lingeringuncertainties that have ensued, NSFfunding has sustained growth,” he wrote.NSF deputy director Cora Marrett isexpected to be named acting directoruntil Suresh’s replacement is found.Starting bell sounds for CHIMEConstruction has begun on what will beCanada’s largest radio telescope. TheC$11m Canadian Hydrogen Intensity-Mapping Experiment (CHIME) inPenticton, British Columbia, is the firstresearch telescope to be built in thecountry in more than 30 years. CHIMEboasts a 100 × 100 m collecting area,which will be filled with 2560 low-noisereceivers built with components adaptedfrom the mobile-phone industry. Signalscollected by the CHIME telescope will bedigitally sampled nearly one billion timesper second, then processed to producean image of the sky. Astronomers willuse the telescope to map a quarter ofthe observable universe to help betterunderstand the nature of dark energy.Liangying Xu: 1920–2013The Chinese physicist Liangying Xu, whowas a fierce advocate of democracy inChina, died on 28 January at the age of92. Xu was born in the eastern Chineseprovince of Zhejiang on 3 May 1920 andstudied physics at Zhejiang University.He later became a member of theChinese Academy of Sciences (CAS),serving as a censor for papers that weregoing to be sent abroad for publication.In 1957 Xu took part in the “HundredFlowers” campaign to speak out over theCommunist Party’s failings, for whichhe was sent to his home village wherehe worked on a farm and also begantranslating Einstein’s works. Followingthe death of Communist party chairmanMao Zedong in 1976, banished scientistsreturned from the countryside andLiangying regained his job at the CAS andsubsequently published a three-volumecollection of Einstein’s works.Physics World March 2013 13

85595PTA5201014/07/201014:14Page183442PTA5201023/04/201012:29Page120101HydrogenHydrogen11.0079H1.0079 0.090-252.87 0.090-252.87LithiumLithium3Li6.9416.9410.54180.50.54180.5SodiumSodium111122.99022.9900.9797.70.9797.7PotassiumPotassium19K39.09839.0980.860.8663.463.4RubidiumRubidium37NaRb85.46885.4681.531.5339.3 39.3Caesium Caesium55Cs132.911.8828.4Francium87Fr[223]––2BerylliumBeryllium4Be9.01229.01221.8512871.851287MagnesiumMagnesium1212Mg24.30524.3051.741.74650650CalciumCalcium20Ca40.07840.0781.551.55842842StrontiumStrontium38Sr87.6287.622.632.63777 777Barium Barium56Ba137.333.51727Radium88Ra[226]5.070057-70*89-102**ADVENTElement Name18Element Name18StandardAtomicHeliumAtomicHeliumNo. SymbolNo. Symbol2HeAtomicweightCatalogue Items24.0026HeAtomicweightDensity Solids& Liquids (g/cm 3 )Gases(g/l)4.0026Density Solids& Liquids (g/cm 0.177M.pt./B.pt.(˚C)3 )Gases(g/l)13 14 15 16 17 0.177 -268.93M.pt./B.pt.(˚C) Meltingpoint(Solids&Liquids)•Boilingpoint(Gases)13 14 15 16 17 -268.93Boron Carbon Nitrogen Oxygen Fluorine NeonBoron Carbon Nitrogen Oxygen Fluorine Neon5566778899F 1010NeRESEARCH MATERIALSB C N O F Ne10.811 12.011 14.007 15.999 18.998 20.18010.8112.4612.0112.2714.0071.25115.9991.42918.9981.69620.1800.9002.4620762.2739001.251-195.791.429-182.951.696-188.120.900-246.082076 3900 -195.79 -182.95 -188.12 -246.08Aluminium Silicon Phosphorus Sulphur Chlorine ArgonAluminium Silicon Phosphorus Sulphur Chlorine Argon1313Al 1414Si 151516161717Cl 1818Al Si P S Cl Ar Ar26.982 28.086 30.974 32.065 35.453 39.94826.9822.7028.0862.3330.9741.8232.0651.9635.4533.21439.9481.78410 11 12 2.70660.32.3314141.8244.21.96115.23.214-34.041.7843 4 5 6 7 8 9 10 11 12-185.85660.3 1414 44.2 115.2 -34.04 -185.85Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine KryptonScandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton21 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 3622232425262728 Ni 2930 Zn 31 Ga 32 Ge 33 As 34 Se 35 Br 36Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Kr44.95644.95647.86747.86750.94250.94251.99651.99654.93854.93855.84555.84558.93358.93358.69358.69363.54663.54665.3965.3969.72369.72372.6472.6474.92274.92278.9678.9679.90479.90483.8083.802.992.994.514.516.116.117.147.147.477.477.877.878.908.908.918.918.928.927.147.145.905.905.325.325.735.734.824.823.123.123.7333.73315411541166816681910191019071907124612461538153814951495145514551084.61084.6419.5419.529.829.8938.3938.3816.9816.9221221-7.3-7.3-153.22-153.22YttriumYttriumZirconiumZirconiumNiobiumNiobiumMolybdenumMolybdenumTechnetiumTechnetiumRutheniumRutheniumRhodiumRhodiumPalladiumPalladiumSilverSilverCadmiumCadmiumIndiumIndiumTinTinAntimonyAntimonyTelluriumTelluriumIodineIodineXenonXenon3940 41 42 43 44 45 46 47 48 49 50 51 52 53 5440414243444546474849 In 50 Sn 51 Sb 52 Te 53 I 54Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Xe88.90688.90691.22491.22492.90692.90695.9495.94[98][98]101.07101.07102.91102.91106.42106.42107.87107.87112.41112.41114.82114.82118.71118.71121.76121.76127.60127.60126.90126.90131.29131.294.474.476.516.518.578.5710.2810.2811.511.512.3712.3712.4512.4512.0212.0210.4910.498.658.657.317.317.317.316.706.706.246.244.944.945.8875.8871526 1526 1855 1855 2477 2477 2623 2623 2157 2157 2334 2334 1964 1964 1554.9 1554.9 961.8 961.8 321.1 321.1 156.6 156.6 231.9 231.9 630.6 630.6 449.5 449.5 113.7 113.7 -108.05 -108.05Lutetium Lutetium Hafnium Hafnium Tantalum Tantalum Tungsten Tungsten Rhenium Rhenium Osmium Osmium Iridium Iridium Platinum Platinum Gold Gold Mercury Mercury Thallium ThalliumLeadLead Bismuth Bismuth Polonium Polonium Astatine Astatine Radon Radon7173 74 75 76 77 78 79 80 81 82 83 84 85 86727374757677 Ir 78798081 Tl 82 Pb 83 Bi 84 Po 85 At 86Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Rn174.97178.49180.95 180.95 183.84 183.84 186.21 186.21 190.23 190.23 192.22 192.22 195.08 195.08 196.97 196.97 200.59 200.59 204.38 204.38 207.2 207.2 208.98 208.98 [209] [209] [210] [210] [222] [222]9.8413.3116.65 16.65 19.25 19.25 21.02 21.02 22.61 22.61 22.65 22.65 21.09 21.09 19.30 19.30 13.55 13.55 11.85 11.85 11.34 11.34 9.78 9.78 9.20 9.20 – – 9.73 9.73165222333017 3017 3422 3422 3186 3186 3033 3033 2466 2466 1768.3 1768.3 1064.2 1064.2 -38.83 -38.83 304 304 327.5 327.5 271.3 271.3 254 254 302 302 -61.85 -61.85LawrenciumRutherfordiumDubniumSeaborgiumBohrium Bohrium Hassium Hassium Meitnerium Meitnerium DarmstadtiumRoentgeniumRoentgenium CoperniciumCopernicium Ununtrium Ununtrium UnunquadiumUnunquadiumUnunpentiumUnunpentiumUnunhexiumUnunhexiumUnunseptiumUnunseptium Ununoctium Ununoctium103109 110 111 112 113 114 115 116 104 m 105106107108109110111112113 114 115 117 118 116Lr Rf Db Sg Bh Hs Mt Ds Rg CnUuq117 118Uut Uup Uuh Uus Uuo[262][265][268][271][272] [272] [270] [270] [276] [276] [281] [281] [280] [280] [285] [285] [284] [284] [289] [289] [288] [288] [293] [293] [–] [–] [294] [294]–––––––––––––––– –– –– –– –– –– –1627––––––––––––––– –– –– –– –– –– –Periodic Table of the Elements€Dataprovidedbykindpermissionofwww.webelements.com*Lanthanoids**ActinoidsLanthanum57La138.916.146920Actinium8989ActiniumAcAc[227]10.071050[227]10.071050Cerium58Ce140.126.689795Thorium90Th232.0411.721842PraseodymiumNeodymium5960Pr140.916.64935231.0415.371568Nd144.246.801024ProtactiniumUranium9192PaU238.0319.051132Promethium61Pm[145]7.2641100Neptunium93Np[237]20.45637Samarium62 62Sm150.367.3531072Plutonium94Pu[244]19.816639Europium63 63Eu151.965.244826 826Americium95 95Am[243]––1176Gadolinium64 64Gd157.257.9011312Curium96 96Cm[247]13.511340Terbium65 65Tb158.938.2191356 1356Berkelium97 97Bk[247]14.78986 986DysprosiumHolmium66 66 67 67Dy162.508.5511407 1407[251]15.1 15.1900 900Ho164.938.795 8.7951461 1461Erbium Erbium68 68Er Er167.269.066 9.0661497 1497CaliforniumEinsteiniumFermium98 98 99 99 100 100CfEs[252] [252]– –860 860Fm[257] [257]– –1527 1527Thulium Thulium69 69Tm168.93 168.939.321 9.3211545 1545[258] [258]– –827 827Ytterbium70 70Yb173.04 173.046.57 6.57824 824MendeleviumNobelium101 101 102 102MdNo[259] [259]– –827 827Tel + 44 1865 884440Fax + 44 1865 884460info@advent-rm.comMETALS & ALLOYS for Research / Development & IndustrySmall Quantities • Competitive Prices • Fast ShipmentAdventResearchMaterialsLtd•Oxford•EnglandOX294JA advent-rm.comwww.cryogenic.co.ukCRYOGEN-FREE MEASUREMENT SYSTEMS5 TO 22 TESLA (CFMS)SQUID Magnetometer (S700X)Cryogen Free/Re-condensing systemCryogen-free super-conducting magnets to 22 TeslaNo liquid helium neededVariable temperature sample space (1.6 K - 400 K)Highly stable magnetic fieldHigh Temperature Insert with temperatures up to 1000 KHe-3 Insert with temperatures down to 300 mKTemperatures down to 50 mK with a cryogen-freeDilution RefrigeratorHigh power Pulse TubeHigh homogeneity cryogen free 7 Tesla magnetCompletely dry or requires no re-fill of liquid heliumLow maintenance Pulse Tube cryocoolerAC and DC 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physicsworld.comNews & AnalysisResearch fundingStudy finds US scientists guilty of ‘double dipping’Significant numbers of US scientistshave received money frommore than one agency for the sameor nearly identical grant applications,according to new analysis byphysicist Harold Garner at VirginiaTech’s Virginia Bioinformatics Institute.The analysis, which was carriedout with data-mining software that isalso used to detect plagiarism, estimatesthat the cost of this “doubledipping” could have totalled around$70m over the past 10 years.The new analysis follows a reportby the US Government AccountabilityOffice in February 2012 thatsuggested that there could be significantwaste of funding throughduplication. Garner’s team focusedon data from more than 850 000grant applications that can be publiclyaccessed from the websites ofscience-related government agenciessuch as the National Science Foundation(NSF) and the Department ofEnergy (DOE). “Since our softwarehad found plagiarism, we knew wecould analyse duplication,” Garnertold Physics World.The investigation revealed 167pairs of very similar applications,although because the websites didnot contain complete grant files,the team could not determine howsimilar the pairs were. However,a follow-up study by Nature provideddocumentation on 22 pairsof very similar grants. “There isn’tany doubt that duplication of grantapplications is going on,” says Garner.“The doubt is about the intensityof it.” Indeed, Garner suspects thathis software could have missed manyother cases of duplication.US research agencies are awarethat there is a problem. The NSF,for example, requires notificationfrom its grant recipients if theyreceive any funding for the sameproject from other sources. But lastNovember, electrical engineer CraigGrimes, formerly of PennsylvaniaState University, was sentenced to41 months in prison for a series ofresearch grant frauds that includedaccepting grants from the NSF andOne for the priceof twoAn analysis of grantsubmissions carriedout by Harold Garnerat the VirginiaBioinformaticsInstitute has foundexamples ofresearchers beingawarded fundingfrom multiplesources based onthe same grantapplication.the DOE for a project on the conversionof carbon dioxide into hydrocarbonsusing solar energy. Meanwhile,in 2010 the NSF banned electricalengineer Guifang Li of the Universityof Central Florida from applyingfor funding for two years, afterhe “failed multiple times to notifythe NSF of his previous Air Forcefunding”. Li argued that, while histwo proposals resembled each other,they would have produced differentprojects. In fact the issue of grantapplications that are similar but notthe same makes it difficult to judgegrant applicants’ motives.Although the study does notbreak down instances of double dippingaccording to discipline, Garnerpoints out that many physics grantsinvolve large groups and significantfunding, which means it is less vulnerableto duplication than subjectssuch as biomedicine that mostlyinvolve small teams and individualinvestigators. Garner thinks tightbudgets and the low chance of winningsupport are why some scientistsare forced to submit identical oralmost identical grant applications.“This underfunding has a number ofconsequences, one of which is raisingthe temptation for individuals tocross the line,” he says.Peter GwynneBoston, MACroatiaReforms ignite row over how to best evaluate researchThe Croatian government has adopteda draft reform proposal that aims toimprove research funding, open upmore posts for young scientists andstrengthen how it deals with misconductin research. Although the reformsstill have to be passed by parliamentbefore becoming law, they havealready sparked fierce debate withinthe academic community in Croatia.Indeed, researchers in the country havebeen divided for several years betweenthose demanding a move to a moremeritocratic system – in which fundingis linked to a researcher’s publicationrecord – and those trying to block suchreforms for fear they would lead Croatiatowards commercializing its science.Most top scientists, includingCroatian researchers working abroad,want science funding to depend purelyon quality and excellence measuredby the number of a researcher’spublications and the impact thosepapers have. However, others sayscientists in Croatia can only do betterscience if they have more funding andthat the government should insteadcreate a national science strategybefore changing the laws.The debate, which has been rumblingfor some time, was reignited by adamning study published in Januaryby the Institute for Social Research inZagreb of the performance of socialscientists in Croatia. It found thatbetween 1991 and 2005 more than60% did not publish any books, whilefewer than 5% published in internationaljournals listed in Thomson Reuters’ WebMost topscientistswant sciencefunding todepend purelyon quality andexcellenceof Science database.Marijan Herak, a geophysicist fromthe University of Zagreb, supportsthe proposals but complains about alack of a proper bibliometric analysisbefore the writing of the draft reforms.“If our system is going to be changed– and it needs to be changed – thenits inefficiency should be objectivelyestablished and documented,” he says.“But this has not happened.” Indeed,in January Herak undertook an as-yetunpublishedbibliometric study of theoutput of Croatian scientists, which – heclaims – shows they fare well comparedwith their counterparts in otherdeveloped nations in terms, for example,of the number of publications relative tototal spending on science.Mićo TatalovićPhysics World March 2013 15iStockphoto/nilgun bostanci

News & Analysisphysicsworld.comL’Aquila scientists appeal convictionFormal appeals are to be made by the seven researchers who werecharged with manslaughter for advice they gave prior to the 2009L’Aquila earthquake, as Edwin Cartlidge reportsLawyers representing the seven scientistsand engineers convicted of manslaughterfor advice they gave aheadof the deadly L’Aquila earthquakein 2009 are expected to have lodgedformal appeals against the verdictin the first few days of March. Theresearchers’ conviction last October– and the six-year jail sentenceshanded down to each of the accused– shocked many in the scientific worldand beyond, triggering warnings thatmany experts would now be scaredto give advice for fear of prosecution.Francesco Petrelli – lawyer for convictedvolcanologist Franco Barberi– said that the verdict will be “subjectto a crossfire of criticisms”.The start of the appeals processcomes some six weeks after thetrial judge, Marco Billi, released a943-page document explaining hisreasoning for the conviction andthe sentences. Largely following theargument put forward by L’Aquila’spublic prosecutor, Billi states thatthe defendants’ “level of guilt is particularlyhigh” and that this guilt isaccentuated by their “conscious anduncritical” participation in a “mediaoperation” ordered by the then headof Italy’s Civil Protection DepartmentGuido Bertolaso. The six-yearprison terms imposed by Billi, whichwould not come into effect until theappeals process has been completed,are two years longer than thoserequested by the prosecutor.The seven experts all took part ina meeting of a government advisorypanel called the National Commissionfor the Forecast and Preventionof Major Risks that was held inL’Aquila on 31 March 2009 – six daysbefore the quake. The meeting hadbeen convened by Bertolaso in thewake of an ongoing “swarm” of smalland medium-sized tremors over theprevious few months. But Billi sayshe does not condemn the scientistsfor failing to predict the earthquake,which he adds is not possiblewith existing scientific knowledge.Instead, he takes issue with themfor having carried out a “superficial,approximate and generic” risk analysisin the light of the swarm. Thatinadequate analysis, he says, had an“unequivocal reassuring effect” onBig impactBuilding damage inthe village of Onna,near L’Aquila in Italy,caused by the April2009 earthquake.How can atrial againstscientists’knowledgebe decidedwithoutrecourse to theshared canonsof internationalscience?the local population, leading someresidents to stay indoors on the nightof the quake when otherwise theywould have sought refuge outside,leading to 29 deaths.Billi explains that the experts werenot tried on the basis of the scientificcontent of their statements butinstead on whether they acted withdue “diligence, prudence and skill”.“This is not a trial against science,”he writes, “but a trial against sevenpublic officials...who carried out anevaluation of the seismic risk thatviolated the rules of analysis, forecastand prevention regulated by the law.”During the trial Marcello Melandri– the legal representative ofgeophysicist Enzo Boschi, who wasanother of those convicted – arguedthat the prosecution had not properlydistinguished the responsibilitiesof each of the seven individuals,pointing out that many of the mostcontroversial comments were madebefore the meeting by just one ofthe indicted – hydraulic engineerBernardo De Bernardinis, who wasthen deputy head of the Civil ProtectionDepartment. Those commentsincluded the notion that the swarmwas positive because it dischargedenergy from the fault, which manywitnesses in court said persuadedtheir relatives to stay inside on thenight of the earthquake. But Billibacks the view of prosecutor FabioPicuti, saying that De Bernardinis’comments amounted to the commission’s“manifesto”, given, he claims,their close match with other statementsmade during the meeting.Alessandra Stefano, representingseismic engineer Gian Michele Calvi,says that Billi’s reasoning is “veryShutterstock/Franco Volpatodisappointing”, arguing that it “doesnothing but repeat the prosecution’smistaken interpretation of the factsand of the law”. Petrelli, meanwhile,argues that Billi has confused theduties of the politicians and administratorswith those of the scientificconsultants, and failed to evaluatethe “substantial difference” betweenthe scientists’ statements on seismicrisk and what was said by the localtelevision stations and newspapers.Petrelli also maintains that Billi, intrying to show that he had not beeninvolved in a “trial against science”,has actually ended up conducting a“trial without science”, in which he(wrongly in Petrelli’s eyes) insistedon not examining the scientific contentof the defendants’ statements.“How can a trial against scientists’knowledge be decided withoutrecourse to the shared canons ofinternational science?” asks Petrelli.The appeals will be heard by threejudges, who, says Stefano, might reacha verdict by the end of the autumn butwhose decision, she adds, is sure tobe challenged in the Supreme Courtby whoever loses at the appeals stage.Petrelli says that the Supreme Courtis not likely to rule on the case beforethe end of 2015.Meanwhile, it appears that a paralleltrial against Bertolaso andDaniela Stati, who was regionalcouncillor for civil protection atthe time of the quake, will not nowtake place. The two had been underinvestigation by the prosecutors foran intercepted phone call that Bertolasomade to Stati the day beforethe scientists met in March 2009,in which Bertolaso referred to the“media operation” with which hewanted “to reassure the public”.Picuti and fellow prosecutor RobertaD’Avolio have now requestedthat the investigation against thepair be terminated. Bertolaso hadclaimed, when giving evidence inlast year’s trial, that his term “mediaoperation” simply referred to hiswish to have the scientists’ deliberationsmade known to the media,rather than spinning the science ina pre-meditated way to reassure thepublic. Picuti and D’Avolio say thisinterpretation cannot be shown tobe false beyond reasonable doubt asneither Bertolaso nor Stati offered“any causally relevant contributionto the formation of the content andoutcome of the meeting”. A judgemust now decide whether to acceptthe prosecution’s request, whichlooks set to be opposed by quakevictims’ relatives.16Physics World March 2013

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physicsworld.comFeedbackLetters to the editor can be sent to Physics World,Temple Circus, Temple Way, Bristol BS1 6HG, UK,or to pwld@iop.org. Please include your address anda telephone number. Letters should be no more than500 words and may be edited. Comments on articlesfrom physicsworld.com can be posted on thewebsite; an edited selection appears herePhysics in IndiaAs a close follower of Physics World and anaspiring science popularizer, I found yourspecial report on India quite timely as itreflects the enhanced efforts to promoteresearch in this country. However, thereport reflects more of the positivechanges that are happening and ignoressome of the serious problems that Indiafaces in producing a high-quality talentpool at the undergraduate level.There are many pockets of excellencein India where high-quality research isconducted. However, these centres ofexcellence are not involved in trainingundergraduates, and the institutionsthat do train undergraduates are notinvolved in research. Most Indian studentstherefore do not go through the processof being nurtured from an early stage byacademics who are actively engaged inresearch, as the best Indian researchersare isolated from the country’smainstream education system.I think a complex set of reasons areresponsible for this situation. One keyconcern is that conducting research hasbeen more of an exception than a normin most Indian universities. In recentyears, many initiatives have been set upto address this problem and a flood ofmoney is now available to people whoare interested in pursuing researchprojects. The problem is that most Indianacademics have not looked at researchfor the better part of their careers, sowhatever research they pursue is likely tobe ad hoc and not original.This scenario has to change if India isto do better. Undergraduate educationshould be introduced in all of the centresthat are currently dedicated only toresearch. It is not just the undergraduateswho stand to benefit from this; professorswill benefit just as much when they areteaching curious young students.Prem PrasadManipal, Karnataka, Indiapremmirthinti@gmail.comI found the special report on Indiawell planned and highly informative,especially the article on “Ignitinga passion for physics among India’stop students”. However, I wish thatthe report had included a separatearticle on the role of informal sciencecommunications in inspiring andinculcating the spirit of inquiry amongschool students. In a country like India,where scientific research is mostly fundedby public money, scientists ought touse the outcomes of their research forsocial benefit. Also, in order to attracttalented students to science and therebyharness their capabilities in fostering anunderstanding of nature, science needsto be made attractive, accessible andcomprehensible in a way that does notdilute its substance.I am the physics curator of the NationalCouncil of Science Museums (NCSM),an autonomous organization under theIndian government’s Ministry of Culturethat is currently led by G S Rautela. Formore than five decades now, the NCSMhas acted as a bridge between membersof the public and science, enhancingunderstanding and appreciation of scienceand technology through a network of47 hands-on and interactive sciencemuseums and centres spread across thecountry. All NCSM units welcome peoplefrom different walks of life, includingstudents in organized groups, familiesand tourists, and visitors are encouragedto get engaged with and participate ininteractive science activities.Comments from physicsworld.comNow hear this: the way people perceive andanalyse sounds is highly nonlinear. We knowthis because there is a restriction (called theGabor limit) on the accuracy of linear methodsin simultaneously determining a sound’s pitchand timing – and humans routinely beat it.Our report on a new study of this phenomenon(“Human hearing is highly nonlinear”,31 January) had physicsworld.com readersspeculating about how hearing works, andwhat further tests might reveal.Maybe humans beat the Gabor limit becausethey’re using more than one process – one thatdoes timing well but is bad at frequency analysisand another that does frequency analysis wellbut is bad at timing. I think it’s possible to devisemore tests to confirm this.philius, IrelandYou cannot get the answer simply by using twoprocesses. They must be correlated. Imagineusing this dual analysis:1. We analysed the frequency and we know therewere three pitches, A, C# and G. But we cannotsay when they occurred.2. We analysed the timings and we know thepitches changed at 1.4 seconds and 1.8 secondsfrom the start of the first one. But we cannot sayImmersed An interactive science exhibit in India.In addition to permanent exhibitiongalleries and science parks, the NCSMregularly organizes travelling exhibitionson contemporary scientific issues. Oneof its most remarkable activities is aspecially designed “museo-bus” thatbrings exhibitions on scientific topicsrelevant to the rural population to remotevillages. The NCSM has also taken onthe responsibility of building sciencecommunication skills among teachers inschools, colleges and universities, andthe professional development of scienceteachers is one of several areas identifiedas a target for future activities.These initiatives – along with manyothers I have no room to mention here –will help to develop a “passion for physics”not only among India’s top students, butalso members of the wider public.Kanchan ChowdhuryNational Council of Science Museums, Indiakkc_154@yahoo.co.inwhat the order of the pitches was.So you see, it is a 2D problem, but the approachyou suggest applies two 1D analysis techniques.edprochakWe already know the ear is highly nonlinear inits amplitude response. Why would we expect itto be linear in any other way? Anyone who hasever played with resonant circuits understandsthat as you raise the Q of the circuit to get betterfrequency selection, the response time (hencethe time to detection at a certain amplitude)increases. The two are directly related.But that applies only to a single resonator.As I understand it, the ear has (very) manyresonators, the cochlear hairs, to pick up eachindividual frequency. It would not surprise me tofind also many resonators at the same frequencybut with different Q, allowing the ear also to pickup timing differences at reasonable amplitudes.Both sets of detector would work to give theeffects seen.ajansenRead these comments in full and add your own atphysicsworld.comNCSMPhysics World March 2013 19

Feedbackphysicsworld.comI read Physics World’s report on India witha keen interest, but I wish it had mentionedthe work of the Institute of MathematicalSciences in Chennai (IMSc), where Iearned my PhD. This is partly becausethe IMSc has just celebrated its goldenjubilee: it was officially inaugurated in1962, after outgrowing its origins as aseries of theoretical physics seminarsthat met in the family home of foundingdirector Alladi Ramakrishnan. Moreimportantly, though, the IMSc – unlikeother institutions of specialized research– is seriously concerned with the spreadof basic education in its neighbourhood.The reason is a deep-rooted belief thatthe future of scientific research dependson quality education at all levels all overthe country.The IMSc’s interest in local educationshows up in the way its facultyenthusiastically engages with the educationof college and university teachers bydelivering more than 100 lectures eachyear and also organizing many workshopsand courses both within and outside itscampus. Its schemes for associate andvisiting scholars are very similar to theones at the Abdus Salam InternationalCentre for Theoretical Physics, in Trieste,Italy, though they operate at a regionallevel. Faculty members write more than50 articles each year on popular scienceand mathematics. Such a vibrant outreachprogramme is an essential way of servingthe Indian physics community.Sameen Ahmed KhanSalalah College of Technology, Omanrohelakhan@yahoo.comEditor’s noteWe had to be selective about whatour special report included, and weacknowledge that it focused more onthe success stories in India’s physicscommunity than the problems – not leastbecause the peaks are easier to spot anddescribe. Physics World will, however, becontinuing to cover physics in India – bothpositives and negatives – in the future.For those who missed it, the report can beread at http://ow.ly/foCk7.Making friends versusnetworkingMarc Kuchner’s article on the importanceto one’s career of making friends, ratherthan merely “networking” (Februarypp44–45) said more about a rather strangeform of networking – based on collectingIntroducing the Model 22CTwo-channel Cryogenic Temperature Controller• Two multipurpose input channels support most cryogenictemperature sensors. Thermocouple inputs are optional.• Operates from

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physicsworld.comCommentPhysics WorldTemple Circus, Temple Way, Bristol BS1 6HG, UKTel: +44 (0)117 929 7481E-mail: pwld@iop.orgWeb: physicsworld.comTwitter: @PhysicsWorldFacebook: facebook.com/physicsworldEditor Matin DurraniAssociate Editor Dens MilneNews Editor Michael BanksReviews and Careers Editor Margaret HarrisFeatures Editor Louise MayorProduction Editor Kate GardnerWeb Editor Hamish JohnstonMultimedia Projects Editor James DaceyWeb Reporter Tushna CommissariatManaging Editor Susan CurtisMarketing and Circulation Gemma BaileyAdvertisement Sales Chris ThomasAdvertisement Production Mark TrimnellDiagram Artist Alison ToveyArt Director Andrew GiaquintoSubscription information 2013 volumeThe subscription rate for institutions is £340 per annum forthe magazine, £645 per annum for the archive. Single issuesare £32. Orders to: IOP Circulation Centre, CDS Global, TowerHouse, Lathkill Street, Sovereign Park, Market Harborough,Leicestershire LE16 9EF, UK (tel: +44 (0)845 4561511;fax: +44 (0)1858 438428; e-mail: iop@subscription.co.uk).Physics World is available on an individual basis, worldwide,through membership of the Institute of PhysicsCopyright © 2013 by IOP Publishing Ltd and individualcontributors. All rights reserved. IOP Publishing Ltd permitssingle photocopying of single articles for private study orresearch, irrespective of where the copying is done. Multiplecopying of contents or parts thereof without permission is inbreach of copyright, except in the UK under the terms of theagreement between the CVCP and the CLA. Authorization ofphotocopy items for internal or personal use, or the internal orpersonal use of specific clients, is granted by IOP PublishingLtd for libraries and other users registered with the CopyrightClearance Center (CCC) Transactional Reporting Service,provided that the base fee of $2.50 per copy is paid directly toCCC, 27 Congress Street, Salem, MA 01970, USABibliographic codes ISSN: 0953-8585 CODEN: PHWOEWPrinted in the UK by Warners (Midlands) plc, The Maltings,West Street, Bourne, Lincolnshire PE10 9PHThe Institute of Physics76 Portland Place, London W1B 1NT, UKTel: +44 (0)20 7470 4800Fax: +44 (0)20 7470 4848E-mail: physics@iop.orgWeb: www.iop.orgThe contents of this magazine, including the views expressedabove, are the responsibility of the Editor. They do notrepresent the views or policies of the Institute of Physics,except where explicitly stated.Physics World is an award-winning magazine and websiteSIPAwards 2012: Best Use of Social MediaMemCom Awards 2012: Best Magazine – ProfessionalAssociation or Royal CollegeQuantum frontiersWelcome to this special issue of Physics World on ideas at the edge of quantum physicsQuantum mechanics, it is safe to say, is one of the most successful theories inphysics. It offers explanations for everything from the behaviour of semiconductorsand transistors to lasers and solar cells – and can even account for howand why stars shine. Yet many of the questions raised by quantum mechanicsabout the subatomic world – and of reality itself – can be mind-blowing. What’smore, the quantum world keeps throwing up new surprises and shows no signsof having been fully explored.This special issue of Physics World shines a light on some of the most interestingcutting-edge work at the frontiers of quantum physics. Vlatko Vedral fromthe University of Oxford kicks things off (pp30–32) by giving you a quick-firereminder of the key points in quantum physics and a brief summary of the mainarticles in this issue. These look at the fascinating new paradigm of “weak measurement”(pp35–40), the application of quantum physics to biology (pp42–45),the use of cold atoms to simulate the quantum world (pp47–51) and the useof entanglement for completely secure satellite communication (pp52–56).Two other articles examine the impact of quantum physics on popular culture(pp25–27) and among the physics community itself (p29).There is much, though, we have missed out for reasons of space, not leastquantum computing. It is a topic we have covered before, notably in our lastspecial issue on quantum physics exactly 15 years ago this month. It was gracedwith one of our most famous cover images (above left), showing Alice and Bob(the names given by convention to those sending and receiving quantum signals)in the style of pop artist Roy Lichtenstein. This month’s specially commissionedcover (above right) echoes our earlier image while underlining that the mysteriesof the quantum world show no sign of abating.●●If you’re a member of the Institute of Physics, do check out our specialquantum-related video and audio content in the digital version of Physics Worldvia our apps or at members.iop.org.physicsworldWe’re busy right now dreaming up a selection of A-list speakers for aspecial Physics World strand in November at the Bristol Festival of Ideas(www.ideasfestival.co.uk). Meanwhile, planning is under way for ourspecial anniversary issue in October, where we’ll be revealing our pick ofthe 25 key people, discoveries, images, applications and questions inphysics now and over the last 25 years.John Richardson; The Comic StripperPhysics World March 2013 23

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physicsworld.comComment: Robert P CreaseCritical Point The quantum momentQuantum mechanics, saysRobert P Crease, has finallyacquired as much culturalinfluence as Newtonianmechanics, though via a verydifferent pathOn the outskirts of Cambridge, next doorto the Lyndsey McDermott hair salon onCastle Street, is a pub called the Sir IsaacNewton. Ask those inside why it’s so namedand drinkers are likely to stare at you, mutteringsomething about British greatness,history or the small fact that Newton waseducated at the university down the road.But the pub’s name reminds us that Newtonnot only is still a highly influential scientist,but remains a popular icon too. Indeed, hisname has also been given to CambridgeUniversity Library’s online course catalogue,to an orbiting X-ray observatoryand a unit of force, as well as a computeroperating system.But the use of Newton’s name as a recognizable“brand” is only the most trivialway in which his work has influenced culture.His greatest legacy – Newtonianmechanics – has affected all human life bydeepening our knowledge of the world, byexpanding our ability to control it, and byreshaping how scientists and non-scientistsalike experience it. The arrival of the Newtonianuniverse was attractive, liberatingand even comforting to many of those inthe 17th and 18th centuries; its promise wasthat the world was not the chaotic, confusingand threatening place it seemed to be– ruled by occult powers and full of enigmaticevents – but was simple, elegant andintelligible. Newton’s work helped humanbeings to understand in a new way the basicissues that human beings seek: what theycould know, how they should act and whatthey might hope for.The Newtonian momentThe Earth and the heavens, according toNewtonian mechanics, were not separateplaces made of different stuff but part of a“uni-verse” in which space and time – andthe laws that govern them – are single, uniformand the same across all scales. Thisuniverse is also homogeneous. It is not ruledby ghosts or phantoms that pop up and disappearunpredictably. Everything has adistinct identity and is located at a specificplace at a specific time. The Newtonianworld is like a cosmic stage or billiard table,where things change only when pushed byAbstract reality Eric J Heller is a Harvard University physicist and chemist who takes computer simulations ofquantum processes and turns them into works of art, such as this piece based on a quantum chaos map.forces. All space is alike and continuous, alldirections comparable, all events caused.This picture strongly influenced philosophers,theologians, writers, artistsand even political thinkers. Indeed, thephilosopher Richard Rorty once referredto “Newtonian political scientist[s]”, whocentre social reforms around “what humanbeings are like – not knowledge of whatGreeks or Frenchmen or Chinese are like,but of humanity as such”. Meanwhile, in2003–2004, the New York Public Librarystaged an exhibition entitled “The NewtonianMoment” to showcase Newton’s culturalimpact and illustrate the revolution inworldview his work brought about. Writingin the exhibition’s catalogue, the historianof science Mordechai Feingold declaredthat the name was chosen because theEnlightenment and Revolution comprised“the epoch and the manner in which Newtonianthought came to permeate Europeanculture in all its forms”.Feingold was using the word “moment”in the way historians do, referring to specialturning points in which a radically new idearecasts past conflicts and tensions to openup new possibilities for the future. Theseturning points are cultural paradigm shiftsthat change what human beings know anddo, and how they interpret their experiences.Features of the Newtonian Moment includethe assumption of universal continuity,certainty, predictability, sameness acrossscales, and the ability of scientists to “takethemselves out” of measurements to seenature as it is apart from human existence.The quantum ambushThe Newtonian Moment lasted for some250 years until the start of the 20th century,when it was ambushed by the quantum.Many scientists initially hoped that theycould find a comfortable place for the quantumon the Newtonian stage, but by 1927 ithad become clear that the quantum underminedmany features of the Newtonianworld, raising unprecedented philosophicalas well as scientific issues. “Never in thehistory of science,” wrote the science historianMax Jammer, “has there been a theorywhich has had such a profound impact onhuman thinking as quantum mechanics”.Some scientists tried to explain what washappening by spreading word of quantumphysics into ever-widening social spheresEric J Heller/Science Photo LibraryPhysics World March 2013 25

Comment: Robert P Creasephysicsworld.comthat lay beyond science itself. These popularizationsencountered an enthusiasticaudience. Artists, novelists, poets andjournalists were fascinated by the non-Newtonian features of quantum mechanics,including discontinuity, uncertainty,unpredictability, and differences acrossscales and areas where scientists couldnot take themselves out of measurements.Quantum terms and concepts – includingquantum leap, uncertainty principle,complementarity, Schrödinger’s cat andparallel worlds – eventually appeared ineveryday language in sparkling prose andflamboyant metaphors.But has the cultural impact of quantummechanics been simply to supply us with astorehouse of unusual, vivid and sometimespretentious or even loopy images? Or hasthe cumulative effect been more serious,and reshaped how even non-scientists viewthe world?To some extent, the quantum’s impacton artists, writers and philosophers wasthat it helped free themselves from theirown Newtonian-inspired misconceptions.A year or two after the discovery of theuncertainty principle in 1927, for instance,the writer D H Lawrence penned the followingpoem fragment.Reuters/Vincent WestI like relativity and quantum theoriesBecause I don’t understand them.And they make me feel as if space shiftedAbout like a swan that can’t settle,Refusing to sit still and be measured;And as if the atom were an impulsive thingAlways changing its mind.Lawrence’s playfully negative remarksmay suggest that his attraction is superficial:he likes relativity and quantum theoriesbecause they connect better with hisexperiences of the world as quixotic andimmeasurable. A similar sentiment wasexpressed by the Austrian-Mexican artistWolfgang Paalen in 1942 when he wroteexcitedly that quantum mechanics heralds“a new order in which science will no longerpretend to a truth more absolute than thatof poetry”. The outcome, he continued, willbe to legitimize the value of the humanities,and “science will understand the value ofart as complementary to her own”.Meanwhile, in 1958 when the New YorkUniversity philosopher William Barrettreviewed 20th century scientific developments,including quantum mechanics, heconcluded that they paint an image of man“that bears a new, stark, more nearly naked,and more questionable aspect”. We havebeen forced to confront our “solitary andgroundless condition” not only throughexistentialist philosophy but also via scienceitself, which has triggered “a denudation,a stripping down, of this being who hasnow to confront himself at the centre of allhis horizons”.Popular physics A couple walks past “Quantum Field-X3”, an installation by Japanese artist Hiro Yamagata,outside the Guggenheim Museum in Bilbao, Spain.Such remarks suggest that humanistsembraced quantum mechanics becausethey experienced the Newtonian universeas a cold and constricting place in whichthey felt defensive and marginalized – withthe news of the strangeness of the quantumdomain coming almost as a relief. But if thisis the only reason humanists found developmentsof the quantum world liberating, itwas surely their own doing, for they wererelying far too seriously on science to beginwith in understanding their own experience.A new humanismIn 1967 the critic and novelist John Updikewrote a brief reflection on the photographsand amateur films taken in Dealey Plazain Dallas, Texas on 22 November 1963, inthe few momentous seconds when PresidentJohn F Kennedy’s motorcade drovethrough and he was hit by an assassin’sbullets. The more closely and carefully theframes were examined, Updike noted, theless sense the things in them made. Whowas the “umbrella man” sporting an openumbrella despite it being a sunny day? Whowas the “tan-coated man” who first runsaway, then is seen in “a gray Rambler drivenby a Negro?” What about the blurry figurein the window next to the one from whichthe shots were fired? Were these innocentbystanders or part of a conspiracy?“We wonder,” Updike wrote, “whethera genuine mystery is being concealed here26 Physics World March 2013

physicsworld.comComment: Robert P CreaseHas the cultural impact of quantummechanics been simply to supply us with astorehouse of unusual, vivid and sometimespretentious or even loopy images?NEW from AmptekDigitalMultichannel Analyzeror whether any similar scrutiny of a minutesection of time and space would yield similarstrangenesses – gaps, inconsistencies,warps and bubbles in the surface of circumstance.Perhaps, as with the elementsof matter, investigation passes a thresholdof common sense and enters a subatomicrealm where laws are mocked, where personshave the life-span of beta particles andthe transparency of neutrinos, and where arough kind of averaging out must substitutefor absolute truth.”Years later, many frames turned out tohave rational explanations. The “umbrellaman” was identified – to the satisfaction ofall but diehard conspiracy theorists. Testifyingbefore a Congressional committee,the man in question said he had been simplyprotesting against the Kennedy family’sdealings with Hitler’s Germany, withthe black umbrella – Neville Chamberlain’strademark fashion accessory – being a symbolfor Nazi appeasers. Far from heraldinga breach in the rationality of the world, theumbrella man was just a heckler.Barrett, being a philosopher, had proposedthat the cultural effect of quantummechanics was to strip us of illusions.Updike, a novelist with a keen interest inscience who followed contemporary developmentsin physics with care, reached adifferent conclusion. His words above indicatethat he saw the impact of quantummechanics on culture to be deeper andmore positive than Barrett had. Indeed,Updike often has his fictional charactersrefer to physics terms in a metaphorical waythat allows them to voice their experiencesmore articulately.The novelist was fully aware that whenscientists look at the subatomic worldframe by frame, so to speak, what theyfind is discontinuous and strange – its happeningsrandom except when collectivelyconsidered. Updike also knew that most ofus tend to find our lives following a similarcrazy logic. Our world does not alwaysfeel smooth, continuous, reliable, lawgoverned,stable and substantive; close up,its palpable sensuousness is often jittery,discontinuous, chaotic, irrational, unstableand ephemeral. Reality today does notseem to have the gentle, universal continuitiesof the Newtonian world, but is morelike that of the surface of a boiling pot ofwater. Using quantum language to describeeveryday conditions may therefore be technicallyincorrect but is metaphorically apt.In another essay, Updike wrote that “ourcentury’s revelations of unthinkable largenessand unimaginable smallness, of abysmalstretches of geological time when wewere nothing, of supernumerary galaxiesand indeterminate subatomic behaviour,of a kind of mad mathematical violence atthe heart of matter have scorched us deeperthan we know”. The scorching broughtabout by such scientific discoveries, Updikeproposed, had given birth to a “new humanism”whose “feeble, hopeless voice” is providedby the “minimal monologuists” ofthe Irish playwright Samuel Beckett – andwhich is also evident in the instantly recognizable“wire-thin, eroded figures” of theSwiss sculptor Alberto Giacometti.The critical pointIf only all human voices were as articulateas Beckett and Giacometti! Too frequently,the use of quantum language and conceptsin popular culture amounts to what thephysicist John Polkinghorne calls “quantumhype”, or the invocation of quantummechanics as “sufficient licence for lazyindulgence in playing with paradox inother disciplines”. This is how it principallyappears in things like TV programmes,cartoons, T-shirts and coffee cups.Updike’s remarks, however, suggest thatquantum mechanics – a theory of awesomecomprehensiveness that has yet to make anunconfirmed prediction – has does morethan help to deepen our knowledge of theworld and to expand our ability to manipulateit. The novelist’s remarks suggest thatquantum mechanics – though a modification,not a replacement, of Newtonianmechanics – has provided us with a rangeof novel and helpful images to interpret ourexperiences of the world in a new way, on ascale equal to or possibly even greater thanNewtonian mechanics. Quantum physicsis metaphorically appealing because itreflects the difficulty we face in describingour own experiences; quantum mechanicsis strange and so are we.Someday, indeed, the era after the NewtonianMoment may come to be known asthe Quantum Moment.Robert P Crease is a professor in the Department ofPhilosophy, Stony Brook University, and historianat the Brookhaven National Laboratory, US,e-mail rcrease@notes.cc.sunysb.eduThe MCA8000D is a full-featureddigital multichannel analyzer intendedto be used with a wide varietyof detector systems.The easy to use 'Pocket MCA' can fitin a shirt pocket.Features oF the MCa8000D• Compatible with traditional analogpulse shaping• MCA and MCS modes• High speed ADC (100 MHz, 16 bit) withdigital pulse height measurement• 8k data channels• Minimum pulse peaking time 500 ns• Conversion time 10 ns• Sliding-scale linearization• Differential nonlinearity

2013Forthcoming institute conFerencesmarch 2013 – aPriL 20156–8 marchadiabatic Quantum computation 2013Institute of Physics, London, UKOrganised by the IOP Quantum Optics, QuantumInformation, Quantum Control Group20–21 marchamig spring meeting 2013National University of Ireland, Maynooth, IrelandOrganised by IOP Atomic and MolecularInteractions Group24–27 marchadvanced school in soft condensed matter:“solutions in the spring”Weetwood Hall, Leeds, UKOrganised jointly by the IOP Liquids and ComplexFluids Group and the IOP Polymer Physics Group25–28 marchthe 40th ioP annual spring conference onPlasma PhysicsUniversity of York, York, UKOrganised by the IOP Plasma Physics Group25–28 marchinterdisciplinary surface science conference(issc-19)East Midlands Conference Centre,Nottingham, UKOrganised by the IOP Thin Films andSurfaces Group7–10 aprilioP nuclear Physics groupconferenceUniversity of York, York, UKOrganised by the IOP Nuclear PhysicsGroup10–12 aprilDielectrics 2013University of Reading, Reading, UKOrganised by the IOP Dielectrics Group15–16 aprilPostgraduate magnetism techniquesWorkshop 2013University of York, York, UKOrganised by IOP Magnetism Group15–16 aprilshape coexistence across the chart of thenuclidesUniversity of York, York, UKOrganised by the IOP Nuclear Physics Group andYork Nuclear Physics Group3–5 Junesecond international conference on opticalangular momentumThe Burrell Collection, Glasgow, UKOrganised by the IOP Optical Group24–26 JunePhysics of emergent Behaviour: From singlecells to groups of individualsThe Grand Hotel, Brighton, UKOrganised by the IOP Biological Physics Group8–12 Julyinternational conference on neutronscattering (icns2013)Edinburgh International Conference Centre,Edinburgh, UK3–6 septemberelectron microscopy and analysis groupconference 2013 (emag)University of York, York, UKOrganised by the IOP Electron Microscopyand Analysis Group4–6 septemberPr’13: international conference onPhotorefractive effects, materials and DevicesThe Winchester Hotel, Winchester, UKOrganised by the IOP Optical Group and the IOPQuantum Electronics and Photonics Group9–11 septemberPhysical aspects of Polymer scienceUniversity of Sheffield, Sheffield, UKOrganised by the IOP Polymer Physics Group16–18 septembersensors & their applications XViiRixos Libertas, Dubrovnik, CroatiaOrganised by the IOP Instrument Science andTechnology Group16–19 septembereuroDisplay 2013 (33rd international Displayresearch conference)Imperial College London, London, UKOrganised by the IOP Optical Group and Societyfor Information Display31 october – 1 november 2013the Violent universeInstitute of Physics, London, UKOrganised by IOP Astroparticle Physics Group18–20 novemberhigh-speed imaging for dynamic testingof materials and structures – 21st DYmattechnical meetingInstitute of Physics, London, UKOrganised jointly by the IOP Applied Physicsand Technology Division and DYMAT Association5–6 Decemberelectrospinning, Principles, Possibilitiesand Practice 2013Institute of Physics, London, UKOrganised by the IOP Dielectrics Groupand IOP Polymer Physics Group201421–25 Julyicsos’11: 11th international conference onthe structure of surfacesUniversity of Warwick, Coventry, UKOrganised by the IOP Thin Films and SurfacesGroup201512–16 aprilelectrostatics 2015Southampton Solent University,Southampton, UKOrganised by the IOP Electrostatics GroupSee www.iop.org/conferencesfor a full list of IOP one-day meetings.The conferences department provides aprofessional event-management service to theIOP’s subject groups and supports bids to bringinternational physics events to the UK.Institute of Physics,76 Portland Place, London W1B 1NT, UKTel +44 (0)20 7470 4800E-mail conferences@iop.orgWeb www.iop.org/conferences

physicsworld.comComment: ForumAgreeing to disagreeA recent poll has highlightedphysicists’ differing views overthe interpretation of fundamentalaspects of quantum theory, butMaximilian Schlosshauerargues that it might not be so bad“If all this damned quantum jumpingwere really to stay,” Erwin Schrödingercomplained to his colleague Niels Bohr in1926, “I should be sorry I ever got involvedwith quantum theory.” Schrödinger, likeBohr, was a founding father of quantumtheory, which had just turned our viewof the world upside down. But he was notalone in his discomfort. Albert Einstein,too, spent years arguing with Bohr overwhether atomic events are fundamentallyrandom or if quantum theory really is all wecan say about physical reality. Indeed, heonce wrote that the theory reminded him of“the system of delusions of an exceedinglyintelligent paranoiac”.Today quantum theory underlies allmodern technology: from transistors,light-emitting diodes and photovoltaics, tonuclear power, magnetic-resonance imaging,lasers and atomic clocks. It is a seeminglyinexhaustible source of new ideasand applications. Quantum-informationscience, for example, is a fresh take oninformation processing, and promisescomputers faster than anything we couldcurrently imagine.No-one, of course, would dispute theimmense successes of quantum theory.But looking at the heart of quantum theoryitself, are we any closer to agreeing whatit is trying to tell us about nature? Or hasnothing really changed since the 1920s?Multiple choicesTraunkirchen in Austria is a picture-postcardvillage. Sitting by a pristine lake andsurrounded by the snow-capped peaksof the Alps, it was the perfect setting fora conference in July 2011 on “quantumphysics and the nature of reality”. Togetherwith Johannes Kofler from the Max PlanckInstitute of Quantum Optics and AntonZeilinger from the University of Vienna,I polled nearly three dozen leading physicists,philosophers and mathematiciansabout their views on quantum theory.The questionnaires consisted of 16multiple-choice questions that probedthe whole spectrum of fundamental questionsabout quantum theory. Knowing howGod does not play dice Einstein disagreed that at aquantum level the universe is random.Quantum physicshas moved fromphilosophy toconcrete actionfierce debates can be regarding the foundationsof quantum theory, we knew thatwe should expect disagreement, but someof the results, which we recently analysed,surprised even us seasoned quantum physicists(arXiv:1301.1069).The respondents were sharply dividedon questions that Bohr and Einstein quarrelledabout. For example, when we askedwhether the physical properties of objectsare well defined before these properties areactually measured, half of the respondentssaid that sometimes they were, while theother half answered with a categorical “no”.And when we asked how best to interpretthe wave functions that physicists use to calculatethe probabilities of their measurementresults, a quarter of respondents saidthe wave functions are something akin to aphysical property. A quarter said they aremerely a representation of what we knowabout the object, while a third preferred amixture of the two options.But what surprised us most were not somuch the disagreements as the preciouspatches of common ground that our pollbrought to light. Quantum theory tells uswith great accuracy how likely it is for anatom to decay at a certain time, but it doesiStockphoto/pixhooknot tell us when it will actually decay – theindividual event, when it happens, seemsto come out of nowhere. Einstein couldnot accept the idea of a universe in whichevents truly randomly fall out one way orthe other, famously declaring that “Goddoesn’t play dice.” But Einstein’s reservationsdidn’t seem to faze our respondents.A two-thirds majority declared Einstein’sview wrong and randomness a fundamentalconcept in nature, and half thought that therandomness we see in quantum phenomenais indeed fundamental and irreducible:that there is no “hidden hand”– no gamblingGod – governing these events.The challenge aheadSo what can we learn from our poll? Onething is clear: quantum physics has movedfrom philosophical debates to concreteaction. Quantum-information science,hailed by an overwhelming majority as abreath of fresh air, is being put to use inlooking at old problems from a new angle.It has helped us not only to get a betterunderstanding of what we can do withquantum theory, but also to find new waysof understanding the theory itself. Variousnew interpretations based around quantuminformation have popped up in the last decade,and our poll shows them rivalling thetraditional interpretations. And instead ofjust slapping an interpretation on a readymadetheory, people now try to actuallyderive quantum theory from simple, physicalprinciples – a new take on the theorythat a majority in our poll found useful.Nearly 90 years after Schrödinger’s exasperatedcry about “this damned quantumjumping”, the jumping goes on and it hasgot us to an awful lot of new places. In fact,two-thirds of our respondents see no limitfor quantum theory’s reach. They thinkit should be possible, in principle at least,to put not only single atoms into quantumsuperpositions, but also everyday objectssuch as a football, or even living organisms.Indeed, this is the kind of situationSchrödinger had ridiculed in his famousparadox, in which quantum theory forcesa cat into an otherworldly state of dead andalive. What Schrödinger had intended asa reductio ad absurdum has today becomejust another challenge to experimentalists.Maximilian Schlosshauer is aquantum theorist at the Universityof Portland in Oregon. He editedElegance and Enigma – acollection of interviews withquantum physicists, e-mailschlossh@up.eduPhysics World March 2013 29

Quantum frontiers: The lowdownphysicsworld.comThe curious state ofquantum physicsSpooky, random and incompatible with gravity – that’s the old news for quantum physics.Now we can measure the state of a wavefunction without it “collapsing” and have plans toquantum-communicate with satellites in space. Vlatko Vedral opens this special issue ofPhysics World by bringing us up to speed with the latest mysteries of the quantum worldVlatko Vedral is aprofessor ofquantum informationtheory at theUniversity of Oxfordand the NationalUniversity ofSingapore, e-mailvlatko.vedral@qubit.orgIn 1900 Lord Kelvin famously pronounced that“there is nothing new to be discovered in physics.All that remains is more and more precise measurement”.The timing of this prediction was spectacularlybad. On 14 December of the same year MaxPlanck published a paper introducing the concept ofquanta, thereby starting a new revolution in physicsthat would lead us to a completely different understandingof the world.Over the following three decades quantum physicswas fully developed, and applied to explain a widerange of phenomena. It now accounts for the basicproperties of small objects such as atoms and subatomicparticles, as well as the world of intermediateobjects such as solids, describing, for example, theirconductivity and superconductivity. Quantum physicsequally applies to astronomically large objects,such as stars, explaining why and how they shine, aswell as correctly predicting the size of white dwarfs.Even spiders use quantum physics when crawling upvertical walls without succumbing to gravity.But despite the success of quantum physics, thereis one thing it does not explain: gravity – the onlyfundamental force that is still impervious to quantization.Some people think that this means gravity isnot a fundamental force after all, but a consequenceof something else (and hence we might not need toquantize it). Others, most notably the University ofOxford physicist Roger Penrose, maintain that quantumphysics will ultimately crush under the weightof gravity.Quantum physics departs from classical physicsin two key aspects. First, it acknowledges that themost fundamental events in the microscopic worldare genuinely random, i.e. that there is no algorithmfor predicting when an atom will emit a photon orwhen an incoming photon will reflect from your sunglasses.Albert Einstein, who was a determinist, complaineda great deal about randomness in quantumphysics, most memorably in discussions with NielsBohr, using the now-famous catchphrase “God doesnot play dice”. The second big departure in quantumphysics is the existence of correlations – how measurementson one system give results related to measurementson another – which are independent ofspace and time, and connect objects into a networkof interdependent entities. Erwin Schrödinger calledthese correlations “quantum entanglement”, whileEinstein complained about this aspect of quantumphysics even more than about randomness, dismissingentanglement as “spooky action at a distance”.Both properties of quantum physics that Einsteindisliked have, however, since been confirmedin numerous experiments. Quantum randomnessis now being used in cryptography to improve thesecrecy of communications and quantum entanglementprovides the basis for many of the fast-developingquantum technologies. Indeed, last year’s NobelPrize for Physics went to David Wineland and SergeHaroche for making the first steps in this direction.Behind both the randomness and the spooky actionis the notion of quantum superposition, namely thefact that quantum systems can exist in many differentstates at the same time. However, we still do notreally understand in which situations the superpositionprinciple is valid, nor do we really understandwhat it would mean for a macroscopic object to be intwo or more different states at the same time.For a theory as successful as quantum physics, itis indeed curious that we are still arguing about itsmeaning. It seems that the macroscopic world welive in is largely governed by classical physics and itis very different from the world that quantum objectsoccupy. But, of course, it must be possible to derivethe classical world from the quantum world. Afterall, large objects are collections of many atoms, eachof which behaves fully quantum mechanically.The connection between quantum and classicalphysics is provided through the notion of a quantummeasurement. Properties of quantum systems,such as their positions and momenta, are generallyindeterminate until we make a measurement. It isonly by measuring, say, the position of an atom thatwe imprint a definitive location on it. However, thismeasurement at the same time makes the atom’svelocity uncertain. Quantum measurements are like30Physics World March 2013

physicsworld.comQuantum frontiers: The lowdownThe Comic Stripperfootsteps on a dusty road – the firmer they are inestablishing footprints, the more dust they raise, andthis cloud of dust prevents us from seeing the footprintsclearly in the future.Curiouser and curiouserTo understand the unintuitive nature of quantummeasurement we must first understand what kind ofa process a measurement is. According to the standarddogma of quantum physics, quantum systemsevolve differently when measured from how theyevolve when they are “free”, i.e. when they are leftalone. Observation, in other words, affects quantumbehaviour (unlike in classical physics where measuringa car’s speed does not change how fast the vehicleis going). However, between the free evolutionand the full measurement there is a continuum ofpossibilities, known by the name of weak measurements.When these were introduced in 1988 by YakirAharonov and colleagues, they caused a great deal ofexcitement. Weak measurements obtain informationabout the system (albeit only partial), but they do notchange the state much (hence the name “weak”).This leads to the possibility of undoing the quantummeasurement, at least with a high probability. “Uncollapsingthe collapse” sounds like a contradictionin terms, but the key issue is that the measurement isonly weak. Other quantum paradoxes can be viewedthrough weak measurements, as Aephraim Steinbergand colleagues explain elsewhere in this issue(pp35–40).Even without fully understanding the picture of thePhysics World March 2013 31

Quantum frontiers: The lowdownphysicsworld.comVolker Steger/Science Photo LibraryBeam me upEntangled photonscan be used forquantumteleportation,quantum computingand possibly evensecure satellitecommunications.world according to quantum physics, we can still usequantum systems to develop new technologies. Oneof the key advantages of quantum systems is theiruniversality – in other words, every quantum systemof sufficient complexity should be able to simulateefficiently every other quantum system. One of themost developed quantum simulators at present usesatoms cooled down to near absolute zero. The interactionsbetween these cold atoms can be tuned sowell in the laboratory that they can be made to interactin many different ways, allowing them to simulatethe behaviour of other systems. This is useful firstand foremost because some physical systems, suchas high-temperature superconductors, are so complicatedthat it is difficult to determine their exactquantum description by measuring them directly.Simulating their behaviour with atoms lets us extractwhat we believe to be the essence. More over, we canalso simulate the behaviour of systems we are noteven sure exist in nature.For example, Majorana fermions are meant to befermionic particles (like electrons), but at the sametime they are their own antiparticles (unlike electrons).At present only bosons, such as photons, areknown to also be their own antiparticles so we donot really know if Majorana fermions exist. Interestingly,this does not prevent us from simulating themwith cold atoms. But is our ability to simulate thingsthat nature does not create itself a deep and fundamentalproperty of the universe? Or is nature’s wayof making Majorana fermions first to make humanswho then figure out how to artificially make (i.e.simulate) Majorana fermions? To paraphrase Bohr,a physicist is just a Majorana fermion’s way of creatingitself. Immanuel Bloch explores this fascinatingtopic for us on pages 47–50.Beyond the physics labQuantum physics may often sound like science fiction,but surely Bohr, Einstein or any of its founderswould never have believed that it might one day bepossible to do quantum experiments in space. Themain motive for taking quantum experiments to thisnew frontier is that if our future communication technologyis to be fully quantum, it will involve quantumcommunication between quantum computers basedon Earth and on satellites. The current world recordin distant quantum-information processing is heldby Anton Zeilinger and colleagues, who teleporteda quantum bit across a distance of 143 km betweenthe Canary Islands of La Palma and Tenerife. Thisterrestrial record will be smashed once we move intospace – the fact that there are very few atoms aroundeliminates a great deal of the noise we have to facewhen doing experiments on Earth.Performing quantum experiments in space willalso allow us to test fundamental physics theories inregimes we have never before been able to access.That is because it will let us send signals over largedistances, between platforms moving at large relativespeeds, all in near-vacuum conditions. Indeed, certaintests of alternative theories to quantum physics,such as Penrose’s gravitationally induced collapse,are only realistically possible in space. The problemis the measurements required are very sensitive sincethe effects postulated at the boundary of quantumphysics and gravity are rather meagre and any otherpotential noise needs to be eliminated. For more onthis fascinating topic of space-based quantum physics,check out the article by Brendon Higgins andThomas Jennewein (pp52–56).Quantum physics is also proving useful in ourunderstanding of biology, which has traditionallybeen based on classical physics given that biologicalmole cules are so large, warm and wet. Afterall, systems that interact strongly with their environment(and so are warm and wet) cannot behavecoherently because the environment itself impedesquantum coherence. Moreover, large moleculeshave many more ways in which quantum coherencecan be destroyed. However, we are now discoveringthat biology may use some of the more sophisticatedquantum tricks to improve its processing.One interesting case, which Jim Al-Khalili explains,is the possibility that DNA mutations are the resultof the quantum tunnelling of hydrogen (pp42–45).Other fascinating examples are bacteria implementinga quantum random walk to optimize photosynthesis,birds using entangled electrons to determinethe inclination of the Earth’s magnetic field and theamazing possibility that we humans and other animalscan smell quantum superpositions.Anybody’s guessSo what of the future? I predict that in 2013 we willsee the first implementation of quantum teleportationbetween satellites. We will also see the firstcold-atom simulation of non-Abelian anyons (particleswith a behaviour that lies somewhere betweenfermions and bosons). We will have more evidencethat biological energy transport is fundamentallyquantum mechanical. We will almost certainly stillpuzzle over the meaning of quantum measurement.And finally, I am convinced that another Nobel prizewill be given for testing quantum-mechanical effects,most likely the existence of the Higgs boson.My predictions will almost certainly be wrong, buteven if they are, quantum physics is guaranteed tokeep us tantalized for many years to come. n32Physics World March 2013

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physicsworld.comQuantum frontiers: Weak measurementCC BY Timm WeitkampIn praise of weaknessQuantum physics is being transformed by a radical new conceptual and experimental approachknown as weak measurement that can do everything from tackling basic quantum mysteries tomapping the trajectories of photons in a Young’s double-slit experiment. Aephraim Steinberg,Amir Feizpour, Lee Rozema, Dylan Mahler and Alex Hayat unveil the power of this new technique“There is no quantum world,” claimed Niels Bohr,one of the founders of quantum mechanics. This powerfultheory, though it underlies so much of modernscience and technology, is an abstract mathematicaldescription that is notoriously difficult to visualize– so much so that Bohr himself felt it a mistake toeven try. Of course, there are rules that let us extractfrom the mathematics some predictions about whatwill happen when we make observations or measurements.To Bohr, the only real task of physics was tomake these predictions, and the hope of actually elucidatingwhat is “really there” when no-one is lookingwas nonsense. We know how to predict what you willsee if you look, but if you do not look, it means nothingto ask “What would have happened if I had?”.The German theorist Pascual Jordan went further.“Observations,” he once wrote, “not only disturbwhat is to be measured, they produce it.” What Jordanmeant is that the wavefunction does not describereality, but only makes statistical predictions aboutpotential measurements. As far as the wavefunctionis concerned, Schrödinger’s cat is indeed “aliveand dead”. Only when we choose what to measuremust the wavefunction “collapse” into one state oranother, to use the language of the Copenhageninterpretation of quantum theory.Over the last 20 years, however, a new set of ideasabout quantum measurement has little by little beengaining a foothold in the minds of some physicists.Known as weak measurement, this novel paradigmhas already been used for investigating a number ofbasic mysteries of quantum mechanics. At a moreAephraimSteinberg,Amir Feizpour,Lee Rozema,Dylan Mahler andAlex Hayat are at theCentre for QuantumInformation andQuantum Controland the Departmentof Physics, Universityof Toronto, Canada,e-mail steinberg@physics.utoronto.caPhysics World March 2013 35

physicsworld.comQuantum frontiers: Weak measurementKrister Shalm and Boris BravermanStrength in weakness Obtained through the principle of weak measurement, this 3D plot shows where a quantum particle is most likely to befound as it passes through a Young’s double-slit apparatus and exhibits wave-like behaviour. The lines overlaid on top of the 3D surface arethe experimentally reconstructed average paths that the particles take through the experiment.way. If we deliberately allow the uncertainty in theinitial pointer position (and hence the uncertaintyin the measurement) to be large, then although noindividual measurement on a single pointer will yieldmuch information, the disturbance arising from ameasurement can be made as small as desired.At first sight, extracting only a tiny bit of informationfrom a measurement might seem to be a strangething to do. But as is well known to anyone who hasspent hours taking data in an undergraduate laboratory– not to mention months or years at a placelike CERN – a large uncertainty on an individualmeasurement is not necessarily a problem. By simplyaveraging over enough trials, one can establishas precise a measure as one has patience for; at leastuntil systematic errors come to dominate. Aharonovcalled this a weak measurement because the couplingbetween the system and the pointer is assumedto be too weak for us to resolve how much the pointershifts by on just a single trial.Under normal circumstances, the result of a weakmeasurement – the average shift of pointers thathave interacted with many identically prepared systems– is exactly the same as the result of a traditionalor “strong” measurement. It is, in other words, the“expectation value” we are all taught to calculatewhen we learn quantum theory. However, the lowstrength of the measurement offers a whole new setof insights into the quantum world by providing uswith a clear operational way to talk about what systemsare doing between measurements. This can beunderstood by considering a protocol known as postselection(see figure 1).To see what post-selection is all about, let’s considera simple experiment. Suppose we start at timet = 0 by placing some electrons as precisely as we canat position x = 0. We know from Heisenberg’s uncertaintyprinciple that their velocity will be enormouslyuncertain, so we will have essentially no idea wherean electron will be after, say, 1 second. But if we placea detector 1 metre away at x = 1, any given electronwill always have some chance of being spotted thereat t = 1 because the wavepacket has spread out overall space. However, when we make a measurementof where the wavepacket is, it may collapse to be atx = 1, or to be elsewhere.Now suppose we take one of these electrons thatappeared at x = 1, which is what we mean by postselection,and ask ourselves how fast it had been travelling.Anyone with common sense would say that itmust have been going at about 1 m/s, since it got fromx = 0 to x = 1 in 1 s. Yet anyone well trained in quantummechanics knows the rules: we cannot know theposition and the velocity simultaneously, and the electrondid not follow any specific trajectory from x = 0to x = 1. And since we never directly measured thevelocity, we have no right to ask what that value was.To see why Bohr’s followers would not accept theseemingly logical conclusion that the electron hadAs anyone who has spent hourstaking data in an undergraduatelaboratory knows, a large uncertaintyon an individual measurement is notnecessarily a problemPhysics World March 2013 37

Quantum frontiers: Weak measurementphysicsworld.com1 Principles of post-selectiona wavefunctionψstrong (projective)measurementpost selectionkeepdiscard×pointer with largeinitial uncertainity(weak) measurementinteraction regioneach pointer observedat a given orientationbmeasurementinteraction regiondistribution ofobserved pointers0–1+1–2+2discarddiscardfrequency ofpointer positionpossiblepointerpositions..–2 –1 0 +1 +2weak valueIf you do aweak enoughmeasurementof the velocityyou reduce thedisturbancethat themeasurementmakes on theposition of theelectron tonearly zeroPost-selected weak measurements give physicists a whole new view of the quantum world. (a) They involve a system (the wavefunction)interacting with a meter (shown here by a pointer) in a “measurement interaction region”. A separate measurement is made of thewavefunction once it has interacted with the pointer, which collapses the wavefunction either into the desired state (green light) or someother state (red light). (b) The trick in weak measurement is to repeat this process on many identically prepared systems. Each time a redlight goes off, the corresponding pointer is discarded; each time a green light goes off, the pointer is kept. In this way, a collection of pointersis obtained, which all correspond to systems that ended up in the desired final state. Since the measurement was weak, there is a greatuncertainty in pointer position. But since we have many pointers, we can find their average deflection – a number termed the “weak value”.been travelling at 1 m/s, imagine what would happenif you decided to measure the velocity after releasingthe electron at x = 0 but before looking for it atx = 1. At the moment of this velocity measurement,you would find some random result (remember thatthe preparation ensured a huge velocity uncertainty).But the velocity measurement would also disturb theposition – whatever velocity you find, the electronwould “forget” that it had started at x = 0, and endup with the same small chance of appearing at x = 1no matter what velocity your measurement revealed.Nothing about your measurement would suggest thatthe electrons that made it to x = 1 were any more orless likely to have been going at 1 m/s than the electronsthat did not.But if you do a weak enough measurement of thevelocity – by using some appropriate device – youreduce the disturbance that the measurement makeson the position of the electron to nearly zero. So if yourepeat such a measurement on many particles, somefraction of them (or “subensemble”, to use the jargon)will be found at the x = 1 detector a second later. Toask about the velocity of the electrons in this subensemble,we can do what would be natural for any38Physics World March 2013

physicsworld.comQuantum frontiers: Weak measurementclassical physicist: instead of averaging the positionsof all the pointers, average only the subset that interactedwith electrons successfully detected at x = 1.The formalism of weak values provides a very simpleformula for such “conditional measurements”.If the system is prepared in an initial state |i〉 andlater found in final state |f 〉, then the average shift ofpointers designed to measure some observable A willcorrespond to a value of 〈f|A|i〉 / 〈f|i〉, where 〈f|i〉 isthe overlap of initial and final states. If no post-selectionis performed at all (i.e. if you average the shiftsof all the pointers, regardless of which final state theyreach), this reduces to the usual quantum-mechanicalexpectation value 〈i|A|i〉. Without the post-selectionprocess, weak measurement just agrees with thestandard quantum formalism; but if you do postselect,weak measurement provides something new.If you work this formula out for the case we havebeen discussing, you find that the electrons thatreached x = 1 were indeed going at 1 m/s on average.This in no way contradicts the uncertainty principle– you cannot say precisely how fast any individualparticle was travelling at any particular time. But it isstriking that we now know that the average result ofsuch a measurement will yield exactly what commonsense would have suggested. What we are arguing –and this admittedly is a controversial point – is thatweak measurements provide the clearest operationaldefinition for quantities such as “the average velocityof the electrons that are going to arrive at x = 1”. Andsince it does not matter how exactly you do the measurement,or what other measurements you chooseto do in parallel, or even just how weak the measurementis, it is very tempting to say that this value,this hypothetical measurement result, is describingsomething that’s “really out there”, whether or not ameasurement is performed. We should stress: this isfor now only a temptation, albeit a tantalizing one.The question of what the “reality” behind a quantumstate is – if such a question is even fair game for physics– remains a huge open problem.Two-slit interferometersThe possibility of studying such subensembles hasmade weak measurements very powerful for investigatinglong-standing puzzles in quantum mechanics.For instance, in the famous Young’s double-slitexperiment, we cannot ask how any individual particlegot to the screen, let alone which slit it traversed,because if we measure which slit each particle traverses,the interference pattern disappears. RichardFeynman famously called this “the only mystery” inquantum mechanics (see box on p40).However, in 2007 Howard Wiseman at GriffithUniversity in Brisbane, Australia, realized thatbecause of the ability of weak measurements todescribe subensembles we can ask, for instance, whatthe average velocity of particles reaching each pointon the screen is, or what their average position wasat some time before they reached that point on thescreen. In fact, in this way, we can build up a set ofaverage trajectories for the particles, each leading toone point on the final interference pattern. It is crucialto note that we cannot state that any individualparticle follows any one of these trajectories. Eachpoint on a trajectory describes only the average positionwe expect to find if we carry out thousands ormillions of very uncertain measurements of position,and post-select on finding the particle at a later pointon the same trajectory.Our group at the University of Toronto has actuallycarried out this particle-trajectory experiment onsingle photons sent through an interferometer, whichthen combine to create an archetypal Young’s double-slitinterference pattern. Our photons, which allhad the same wavelength, were generated in an opticallypumped quantum dot before being sent downtwo arms of the interferometer and then being madeto recombine, with their interference pattern beingrecorded on a CCD camera. Before the photonsreached the screen, however, we sent them through apiece of calcite, which rotates their polarization by asmall amount that depends on the direction the photonis travelling in. So by measuring the polarizationshift, which was the basis of our weak measurement,we could calculate their direction and thus (knowingthey are travelling at the speed of light) determinetheir velocity. The polarization of the transmittedphoton in effect serves as the “pointer”, carryingsome information about the “system” (in this case,the photon’s velocity). We in fact measured the polarizationrotation at each point on the surface of theCCD, which gave us a “conditional momentum” forthe particles that had reached that point. By adjustingthe optics, we could repeat this measurement ina number of different planes between the double slitand the final screen. This enabled us to “connect thedots” and reconstruct a full set of trajectories (Science332 1170) as shown in figure 1.Back to the uncertainty principleThroughout this article, we have made use of the ideathat any measurement of a particle must disturb it –and the more precise the measurement, the greaterthe disturbance. Indeed, this is often how Heisenberg’suncertainty principle is described. However,this description is flawed. The uncertainty principleproved in our textbooks says nothing about measurementdisturbance but, rather, places limits on howprecisely a quantum state can specify two conjugateproperties such as position, x, and momentum, p,Practical messageDylan Mahler andLee Rozema workingon an optical table inthe authors’ lab atthe University ofToronto, carrying outprecisely the sort ofexperiment thattheorists hadsuggested should bedesigned to defineweak measurementsin the first place.Dylan MahlerPhysics World March 2013 39

Quantum frontiers: Weak measurementphysicsworld.comWeak insights into interferenceIn the famous Bohr–Einstein debates, the fact that an interference pattern ina double-slit experiment disappears if you measure which slit the particle goesthrough was explained in terms of the uncertainty principle. Measuring the particledisturbs its momentum, the argument went, which washes out the interference.However, from a modern perspective, information is fundamental and whatdestroys the interference is knowing which slit the photon goes through – in otherwords, the presence of “which-path” information. In the 1990s there was a ratherheated debate over whether or not a which-path measurement could be carriedout without disturbing the momentum (see, for instance, Nature 351 111 and367 626). However, in 2003 Howard Wiseman at Griffith University in Brisbanecame up with a proposal to observe what really happens when a measurementis performed to tell which slit the photon traverses (Phys. Lett. A 311 285) – anexperiment that our group at the University of Toronto performed for real in 2007using the principle of weak measurement. We were able to directly measurethe momentum disturbance by making a weak measurement of each photon’smomentum at early times, and then measuring strongly what its momentum wasat the end of the experiment – the difference between the two values being theaverage momentum change, roughly speaking (New J. Phys. 9 287).In the original 1990s debate, the two camps had chosen very differentdefinitions of momentum transfer, leading each to prove seemingly contradictoryconclusions about its magnitude. Our experiment, by following Wiseman’sproposal of weak measurement as an operational definition, was thus introducinga third notion of momentum transfer. Remarkably, the result of this experimentagreed with the most important aspects of both original proofs, in some senseresolving the controversy. Even though the different groups chose differentdefinitions, one cannot help but think that all these definitions reveal partof a bigger story about what is really “going on” – otherwise, why should ameasurement carried out using one definition satisfy theorems proved for twoentirely unrelated definitions? This is just one of the open questions that thosewho deal with weak measurements find so fascinating.according to Heisenberg’s formula ΔxΔp ≥ /2, where is Planck’s constant divided by 2p. But as MasanaoOzawa from Tohoku University in Japan showed in2003, it is also possible to calculate the minimumdisturbance that a measurement must impart (Phys.Rev. A 67 042105). As expected, Ozawa found thatthe more precise a measurement the more it mustdisturb the quantum particle. Surprisingly, however,the detailed values predicted by his result said thatit should be possible to make a measurement withless disturbance than predicted by (inappropriately)applying Heisenberg’s formula to the problem ofmeasurement disturbance.At first, it seemed unclear whether one could conceiveof an experimental test of Ozawa’s new relationshipat all. To establish, for example, the momentumdisturbance imparted by measuring position, youwould need to ascertain what this momentum wasbefore the position measurement – and then againafterwards to see by how much it had changed. Andif you did this by performing traditional (strong)measurements of momentum, those measurementsthemselves would disturb the particle yet again, andOzawa’s formula would no longer apply. Nevertheless,two teams of researchers have recently beenable to illustrate the validity of Ozawa’s new relationship(and the failure of Heisenberg’s formula fordescribing measurement disturbance). One experiment,carried out in 2012 by a team at the ViennaUniversity of Technology (Nature Phys. 8 185), reliedon a tomographic-style technique suggested byOzawa himself in 2004, while the other by our groupat Toronto (Phys. Rev. Lett. 109 100404) used weakmeasurement, as suggested by Wiseman and his coworkerAustin Lund in 2010, to directly measure theaverage disturbance experienced by a subensemble.Uncertainty in the real worldWeak measurements not only provide unique toolsfor answering fundamental physical questions, butalso open new directions in practical real-worldapplications by improving measurement precision.Remember that the average pointer shifts predictedfor weak measurements are inversely proportionalto 〈 f|i〉, the overlap of the initial and final states.So if the overlap is small, the pointer shift may beextremely large – larger than could ever occur withoutpost-selection. This idea of “weak value amplification”has in fact been used to perform severalextremely sensitive measurements, including oneby Onur Hosten and Paul Kwiat at the University ofIllinois at Urbana-Champaign to measure the “spinHall” effect of light (Science 319 787) and another byJohn Howell’s group at the University of Rochesterin New York (Phys. Rev. Lett. 102 173601), in whichthe angle of photons bouncing off a mirror was measuredto an accuracy of 200 femtoradians.Of course, there is a price to pay. By adjusting theoverlap between initial and final states to be verysmall, you make the probability of a successful postselectiontiny. In other words, you throw out most ofyour photons. But on the rare occasions when thepost-selection succeeds, you get a much larger resultthan you otherwise would have. (Howell’s grouptypically detected between about 1% and 6% of photons.)Going through the maths, it turns out this is astatistical wash: under ideal conditions, the signal-tonoiseratio would be exactly the same with or withoutthe post-selection. But conditions are not alwaysideal – certain kinds of “technical noise” do not varyquickly enough to be averaged away by simply accumulatingmore photons. In these cases, it turns outthat post-selection is a good bet: in return for throwingaway photons that were not helping anyway, youcan amplify your signal (Phys. Rev. Lett. 105 010405and 107 133603). In fact, measurements enhanced byweak-value amplification are now attracting growingattention in many fields including magnetometry,biosensing and spectroscopy of atomic and solidstatesystems.As often happens in physics, something that beganas a quest for new ways to define answers to metaphysicalquestions about nature has led not only to adeeper understanding of the quantum theory itself,but even to the promise of fantastic new technologies.Future metrology techniques may be much indebt to this abstract theory of weak measurement,but one should remember that the theory itself couldnever have been devised without asking down-toearthquestions about how measurements are actuallydone in the laboratory. Weak measurementsare yet another example of the continual interplaybetween theory and experiment that makes physicswhat it is.n40Physics World March 2013

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Quantum frontiers: Quantum biologyphysicsworld.comNature’s quantum subwaysJim Al-Khalili describes the new experiments and theories exploring whether quantum tunnelling ofhydrogen causes mutations in our DNAShutterstock/Lonely42Physics World March 2013

physicsworld.comQuantum frontiers: Quantum biology“Some of us should venture to embark on a synthesisof facts and theories, albeit with secondhand andincomplete knowledge of some of them – and at therisk of making fools of ourselves.”So said Erwin Schrödinger in 1943 upon his forayfrom quantum physics into genetics. He would soonback up these words with his hugely influential 1944book, What is Life?, in which he predicted that geneticinformation is stored within an aperiodic crystal – anidea that would be confirmed by Francis Crick andJames Watson less than a decade later when theydiscovered the structure of the double helix. Today,a small but increasing number of us would echoSchrödinger’s sentiments, even though the case hasyet to be made conclusively for a causal link betweensome of the weirder aspects of quantum mechanicsand biology.It is certainly true that although many examplescan be found in the literature dating back half acentury, there is still no widespread acceptancethat quantum mechanics – that baffling yet powerfultheory of the subatomic world – might play acrucial role in biological processes. Of course, biologyis, at its most basic, chemistry, and chemistry isbuilt on the rules of quantum mechanics in the wayatoms and molecules behave and fit together. Butbiologists have (until recently) been dismissive of thecounterintuitive aspects of the theory – they feel itto be unnecessary, preferring their traditional balland-stickmodels of the molecular structures of life.Likewise, physicists have been reluctant to ventureinto the messy and complex world of the living cell.Why should they when they can test their theoriesfar more cleanly in the controlled environment ofthe physics lab, where they at least feel they have achance of understanding what is going on? But now,experimental techniques in biology have become sosophisticated that the time is ripe for testing a fewideas familiar to quantum physicists.Sticking togetherOf all the quantum processes suggested as playing arole in biology – which include quantum coherence,superposition and entanglement – one of the leastcontentious and best studied is quantum tunnelling.This is the mechanism whereby a subatomic particle,such as an electron, proton or even a larger atomicnucleus, does not have enough energy to punchthrough a potential barrier (essentially a force field),but instead behaves as a spread-out fuzzy entity thatcan leak through the barrier and so occasionally finditself on the other side. This phenomenon is familiarin physics and is the mechanism responsible for radioactivedecay and nuclear fusion. Quantum tunnellingis also well known in chemistry, for example inthe form of hydrogen tunnelling in hydrogen-bondeddimer molecules, such as benzoic acid.It turns out that even in biology it is now well establishedthat electrons quantum tunnel in enzymes,allowing certain chemical processes to speed up byseveral orders of magnitude. But one particular questionthat I, and others, have been exploring over thepast few years is whether quantum tunnelling of hydrogennuclei (protons) in the form of a hydrogen bondhas a role to play in one of the most important processesin molecular biology: DNA mutation. Hydrogenbonds are stronger than Van der Waals forces butweaker than ionic and covalent bonds, being a happymedium that hold certain organic molecules together.Crucially, they are strong enough to help build stablestructures, but not so strong that they cannot be broken,which is why the structures can be rearrangedinto new configurations. The hydrogen bond is alsoresponsible for stabilizing proteins and for modulatingthe speed and specificity of chemical reactions.In physical terms, the hydrogen bond can bedescribed as a proton trapped in a double, oftenasymmetric, finite potential well. The two potentialminima exist because the proton is happiest beingclose to one or other of the two atoms at each end ofthe bond, with an energy barrier in the middle, whichthe proton can only get over classically if given sufficientenergy. To understand the proton’s behaviourwe need to map the shape of this well, or potentialenergy surface, very accurately. This is no trivial matteras its shape depends on many variables. Not onlyis the bond typically part of a large complex structureconsisting of hundreds or even thousands of atoms,it is also usually immersed in a warm bath of watermolecules and other chemicals. Moreover, molecularvibrations, thermal fluctuations, chemical reactionsinitiated by enzymes and even UV or ionizing radiationcan all affect the behaviour of the bond bothdirectly and indirectly. In addition to all this, andwhat is of most interest here, is that the small massof the proton means it is able to behave quantummechanicallyand very occasionally tunnel throughthe potential barrier from one well to the other (seefor example the 2011 paper by Angelos Michaelidesand colleagues at University College London – Proc.Natl Acad. Sci. 108 6369).This discussion is certainly relevant to DNA, whichconsists of two nucleotide chains wrapped aroundeach other in a double helix. They are held togetherand stabilized by hydrogen bonds, which link the basepairs: adenine to thymine (A–T) and cytosine to guanine(C–G). If we consider the A–T base pair, whichis held together by two hydrogen bonds, then as aresult of the different possible positions of the hydrogenatoms that form the bonds, two different structuresare possible. Normally, the protons form what iscalled the canonical (keto) structure of the base pair(figure 1), but occasionally they can be found shiftedacross to the opposite sides of the hydrogen bonds toform the rare tautomeric (enol) form.After their landmark paper, which was published60 years ago next month, Watson and Crick’s interestsquickly turned to the biological implications ofthe double-helix structure and in a follow-up paperof 1953 they suggested that spontaneous mutation – achange in the genetic code, for example from ATCATto ATCAC – may be caused by a base taking on itshigher-energy, rarer, tautomeric form. A decadelater, the Swedish physicist Per-Olov Löwdin boldlyproposed that the tautomeric base pair that leads toa mutation is formed through double proton transfer,with each particle quantum tunnelling through thebarrier separating the two asymmetric potential wellsJim Al-Khalili is atheoretical nuclearphysicist and holds achair in publicengagement inscience at theUniversity of Surrey,UK. He is also abroadcaster andauthor whose latestbook is Paradox:the Nine GreatestEnigmas in Physicspublished by BantamPress, e-mailj.al-khalili@surrey.ac.ukPhysics World March 2013 43

Quantum frontiers: Quantum biologyphysicsworld.comThis couldprovideinformationon how thetunnellingprocess isaffected withinthe busy, warmenvironment ofa living cell1 Base-pair mutantsNNNadenineHNN(Rev. Mod. Phys. 35 724). The protons spend most oftheir time in their deeper wells, but can occasionallytunnel across to the shallow well to form the tautomericstructure. A mutation can then take place onlyif the rarer tautomeric form remains stable during thereplication process. What could happen, for example,is that an A–T base pair in DNA could turn into itstautomeric form, A*–T*. Then, when the two strandsof DNA split, the tautomer of adenine will now bindto cytosine (A*–C). This would cause an error in thegenetic code (because the new strand now has a Creplacing a T in its sequence) and hence a mutation.Modelling mutationHalf a century on from Löwdin’s double-proton tunnellingproposal, experiments by Lorena Beese andcolleagues at Duke University in the US in 2011 lookto have at least confirmed the hypothesis put forwardby Watson and Crick – that tautomeric forms of DNAbases can cause mutations (Proc. Natl Acad. Sci. 10817644). However, the mechanism by which canonicalbase pairs become tautomeric remains unconfirmed.Many computational chemistry groups around theworld have, over the past two decades, attempted tomodel the process of double proton transfer in theadenine–thymine base pair. (This base pair is chosenbecause it is simpler to model than cytosine–guanine,which is joined by three hydrogen bonds ratherthan two.) In recent years, a method called densityfunctional theory (DFT) has emerged as the frontrunneramong the various computational methodsto model the structure of large molecules and manyatomsystems. In this approach, the properties of amany-electron system can be determined accuratelyby examining its electron density. DFT calculationsare carried out by large computer codes that havebecome so sophisticated that non-aficionados canuse them essentially as black boxes into which onefeeds information about the system of interest (suchas a crystal or a protein). These codes have beensuccessfully used to tackle problems in materialscience, condensed-matter physics, computationalHHONOthymineOne of the two base pairs comprising DNA, the adenine–thymine pairis joined together by two hydrogen bonds in the configuration shown,known as the canonical structure. Occasionally, both hydrogennuclei (protons) in these bonds can switch allegiance and travelalong the dashed lines to be close to the opposite half of the basepair, forming the tautomeric structure. Replication of the base pairwhile in this form leads to an error in the genetic code – a mutation.Nchemistry and, more recently, nuclear structure andmolecular biology.But even incorporating into the calculation thebehaviour and structure of hundreds of atoms thatmake up a section of DNA is not likely to be sufficientto produce a realistic model. Lone DNA isan example of what is known as an “open” quantumsystem, whereby the surrounding environment caninfluence its behaviour. It is known, for example, thatin the case of 5-Bromouracil – a molecule similarto adenine – the presence of water molecules completelyalters the shape of the double well, makingthe rarer tautomeric form more energetically favourablethan the canonical one, suggesting that adeninemight be similarly affected inside the cell.The approach being adopted by my PhD student,Adam Godbeer, at the University of Surrey workingwith theoretical chemists at University CollegeLondon, led by Michaelides, involves using DFT tocalculate very accurately the shape of the potentialenergy surface by taking into account as much of thestructural information of the DNA base pair as possible,constrained as always by numerical complexityand computational power when dealing with manybodysystems. This static potential energy surfaceis then used to calculate the time evolution of theproton tunnelling process. An added complication isthe presence and influence of the external environment,for this is an open quantum system where thesurrounding water molecules must also be taken intoaccount. This leads to what is called a decoherence,or dissipative, term in the quantum-mechanicalequations, which could provide information on howthe tunnelling process is affected within the busy,warm environment of a living cell.In parallel with this theoretical work, an experimentbeing conducted at Surrey, led by molecularbiologist Johnjoe McFadden, is also attempting topin down whether proton tunnelling plays a role intautomeric mutagenesis. The experiment involvesreplacing the protons in the hydrogen bonds withtheir more massive isotope, deuterons, and seeing ifthe mutation rate changes when the heavier isotopeis present. This is done by replicating short strandsof DNA in deuterated water and using a powerfultechnique called a polymerase chain reaction to producemany copies of the strands very quickly. As thedouble helix splits and each strand pairs up with anew one made from the raw material available in itssurroundings, use is made of the deuterium in thewater for some of the hydrogen bonds. If quantumtunnelling plays a role in mutagenesis we mightexpect to see a drop in the mutation rate – since deuterons,with twice the mass of protons, will tunnelmuch more rarely.Complicating factorsUnfortunately, I am learning that nothing is everthat straightforward in biology and – although earlyresults point tentatively towards Löwdin’s proposalbeing confirmed – a number of other quantumnuclear effects must be taken into account. For example,the heavier deuteron means that the vibrationalfrequency of the chemical bond it forms is affected.44Physics World March 2013

physicsworld.comRichard Kail/Science Photo LibraryBreaking barriers Quantum tunnelling of hydrogen in DNA is one of manyquantum processes in nature being explored by physicists and biologists.Heavier atoms will (classically) lead to lower vibrationfrequencies or, viewed quantum mechanically, alower zero-point energy. More energy must thereforebe supplied to break the bond, which in turn lowersthe measured rate. Other quantum nuclear effects,such as zero-point motion, are already known tobe important in hydrogen bonds, and if a protonin a hydrogen bond is replaced by a deuteron thenthe structure of the bond is altered (the Ubbelohdeeffect), as will be the shape of the potential energysurface and hence the tunnelling probability.The bottom line is that absolute quantitative comparisonsbetween theory and experiment are alwaysvery difficult in complex biological systems. While itis known that an isolated nucleotide base in the labcan exist in its rare tautomeric form between 0.1%and 1% of the time, this will not be the same as therate inside living cells where polymerase enzymeshave error-correcting mechanisms that can achievefidelities up to 1 error in 10 8 or better. This errorcorrectingprocess is of course not included in anytheoretical models. In any case, it is known thatmutations take place for a variety of reasons and disentanglingwhat fraction of these might be down toquantum nuclear effects is a huge challenge.Whether or not Löwdin’s hypothesis is confirmed,his 1963 paper should at least be celebrated for astatement he makes in the very first paragraph: “Theelectronic and protonic structure of biologicallyinteresting molecules and systems has to be treatedby quantum chemistry. This has led to the openingof a new field, which has been called sub-molecularbiology or ‘quantum biology’ ”.To my knowledge, that was the first ever use of theterm, showing that even if we are reluctant to creditSchrödinger with first establishing the field of quantumbiology, it is certainly half a century old. nPhysics World March 2013 45

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physicsworld.comQuantum frontiers: Quantum simulationQuantum leaps for simulationImmanuel Bloch describes how recent experiments with ultracold atoms are bringing us closer torealizing Richard Feynman’s dream of a universal quantum simulatorI Bloch, MPQMany of the most interesting phenomena in condensed-matterphysics – from high-temperaturesuperconductivity to quantum magnetism – shareone frustrating characteristic: they are extremelydifficult to simulate on a computer. The reason isnot hard to understand. Suppose we have a systemof N spin-1/2 particles, such as electrons. In order todescribe the quantum state of this system on a classicalcomputer, we would need to store 2 N coefficientsin the computer’s memory. For a small system of onlyN = 300 particles, this equates to a memory size thatexceeds the number of protons estimated to exist inthe entire visible universe. And of course, in orderto perform actual quantum-mechanical calculationson this system, we would also need to do arithmeticaloperations on all of these coefficients. To makematters worse, the size of the memory problem growsexponentially: adding only one more spin-1/2 particleto the problem requires you to double the size ofthe computer’s memory.Condensed-matter physicists have developedclever approximations and numerical methods thatImmanuel Bloch is aphysicist at theLudwig MaximilianUniversity of Munichand scientificdirector of the MaxPlanck Institute ofQuantum Optics inGarching, Germany,e-mail immanuel.bloch@mpq.mpg.dePhysics World March 2013 47

Quantum frontiers: Quantum simulationphysicsworld.comAt a glance: Quantum simulation●●The idea of quantum simulation originated in a 1981 lectureby Richard Feynman, in which he suggested that simple,controllable quantum systems could be used to simulate thequantum dynamics of problems that cannot be modelled by aconventional computer●●Ultracold atoms trapped in optical lattices are a good candidatefor performing such simulations, thanks to the high degree ofcontrol that experimentalists have over important parameterssuch as the position of the atoms and the geometry of the lattice●●Recent experiments have obtained high-resolution images ofatoms trapped in these optical lattices, and also used laserbeams to flip the spins of individual atoms in a controlled way●●Future experiments with ultracold atoms may enable us tosimulate the effects of very high magnetic fields on realmaterials, and perhaps even observe new phases of matterSimulations machine Christof Weitenberg working on the experimental set-up at MPQ.Thorsten Naeser, MPQallow them to work around this fundamental problem,and in many cases these techniques have givenus good answers to specific problems. However, inother systems, especially where the electrons interactstrongly with each other, these approximationsfail or become invalid as a result of the rapid growthof entanglement effects in many-body systems. Thisrapid growth can be especially severe for a systemthat has been pushed far from equilibrium and thenallowed to evolve. But does this mean we have to giveup on trying to understand how these quantum manybodyproblems work? Or is there another solution?Richard Feynman certainly thought there was. Inhis visionary 1981 lecture “Simulating physics withcomputers” Feynman outlined a radically differentapproach to this fundamental problem: he suggestedthat it might be possible to use highly controllablequantum systems to simulate the quantum dynamicsof other – classically intractable – problems. Theidea of a “quantum simulator” was born – a “quantummachine that could imitate any quantum system,including the physical world”.As with many of Feynman’s brilliant ideas, this onehas taken some time to take shape in practice. Withinthe past few years, however, groups around the worldhave begun to build such quantum simulators inmany different physical implementations, includingBose–Einstein condensates, degenerate Fermi gases,photons, trapped ions and arrays of superconductingqubits or quantum dots. These systems all havethe virtue of being tunable, meaning that all theirinteractions, potentials and other parameters can beengineered to suit a certain model. Thanks to thisproperty, there is a very good chance that we will beable to use such model systems to realize completelynew forms of matter under extreme conditions thatcannot be achieved in any other system – and in theprocess, start to investigate some previously intractableproblems.Trapped in a latticeThe root of many condensed-matter problems lies inunderstanding the behaviour of electrons in a solid.In the simplest approximation, such electrons canbe described as moving through a periodic potentialgenerated by the positively charged ionic cores of theatoms that make up the solid, which are arranged ina lattice structure. One way to create such a periodicpotential in the laboratory is to use an “optical lattice”formed by laser beams. When the beams aresuperimposed on each other, their optical interferencegenerates a pattern of regularly spaced potentialwells. These wells are deep enough that atomsthat have been cooled to temperatures just aboveabsolute zero can be trapped in them, like eggs inan egg carton. These ultracold atoms then experiencethe lattice pattern of dark and bright regionsas a perfect, defect-free, periodic potential and canmove from one lattice site to the next via quantummechanicaltunnelling.The great advantage of such a set-up is that manyparameters of this periodic potential are under thecomplete control of the experimentalist. For example,the depth of the wells can be easily changed byadjusting the intensity of the laser beams, and thelattice’s geometry can be shaped by interfering laserbeams under different angles. This flexibility allowsresearchers to create any geometrical pattern, from asimple cubic-type lattice structure to triangular andhexagonal lattices like those found in graphene.In recent years, the collective behaviour of interactingbosonic and fermionic atoms in such opticallattices has been a major focus of investigations withultracold atoms. Then, in 2011, prospects for usingultracold atoms to perform quantum simulationstook a dramatic step forward when two researchteams (led by Markus Greiner at Harvard Universityand Stefan Kuhr and myself in Munich) reportedthat we had successfully obtained high-resolutionimages of individual atoms in an optical lattice. Theresolution of the imaging in these so-called “quantumgas microscopes” is so good that we can discernthe occupation of neighbouring lattice sites. To putthat into perspective, if we had this kind of resolutionin a real electronic material, we would be able to takesingle snapshots of the position of all the electrons inthe material.The way the experiments work is that ultracoldatoms in a Bose–Einstein condensate (BEC) – anexotic state of matter in which all the component48Physics World March 2013

physicsworld.comQuantum frontiers: Quantum simulationatoms share the same wavefunction, and thus behavelike a single “matter wave” – are first trapped in a 2Dplane. The atoms are then transferred into an eggcarton-shapedlattice potential of light, which at thesame time helps to bring the atoms into an interesting,strongly interacting quantum phase. Before theatoms are imaged, the depth of the lattices is suddenlyincreased to stop the atoms moving and holdthem tight in space. Then, a laser beam with a frequencynear resonance with an atomic transition isswitched on, causing the atoms to fluoresce like tinynanoscopic light bulbs. The resulting array of nanobulbscan be imaged using a high-resolution microscopeobjective (figure 1).The precise moment when the first photons of theimaging laser beam are scattered off the atoms iscrucial for the quantum-measurement process. Initially,the atoms are in a complicated quantum superpositionstate of different spatial configurations, witha many-body wavefunction Ψ(x 1 …x N ). The measurementprocess collapses this wavefunction, and theatoms are observed to be in one of many possiblespatial configurations. Image-processing algorithmsallow us to reconstruct the position of each individualatom in the lattice, but the particular configurationof atoms observed in a single snapshot is, ofcourse, completely random. Only by repeating theexperiment many times does it become possible tobuild up a histogram of the occurrences of differentspatial configurations. Examples of such reconstructedparticle positions for two distinct phases ofmatter – a BEC and a Mott insulator – can be seenin figure 2.1 Quantum gas microscopeahigh-resolutionobjectivezy16 µmx(a) Ultracold atoms trapped in a single plane of an optical lattice are imaged using a highresolutionmicroscope that detects the atoms’ laser-induced fluorescence. (b) A typicalimage of atoms trapped in the lattice.2 Imaging different phases of matterMapping fluctuationsJust being able to image single atoms in a latticeis pretty exciting in itself, but it gets better. If youtake a close look at the reconstructed images in figure2 b–c, you will see some gaps, or defects, in thelattice. These “missing atoms” represent individualthermal fluctuations, and they are directly visible ina single shot of the experiment. Being able to see singlethermal fluctuations in such a system gives us anextremely precise thermometer, which has allowedresearchers to determine temperatures down to the100 pK level using just a single image.Perhaps more importantly, the “quantum gasmicroscope” also enables us to directly observe thezero-temperature quantum fluctuations of a manybodysystem. Many readers will have encounteredsuch quantum fluctuations in the classic textbookexample of a single quantum particle in the absoluteground state of a harmonic oscillator. In this simplesystem, the position of the particle remains undeterminedwithin a region given by the extension ofthe ground state wavefunction – in sharp contrastwith the behaviour of a classical particle at zero temperature,for which position and momentum wouldalways be well defined.A quantum many-body system also exhibits suchinherent quantum fluctuations, and when theybecome very strong, these fluctuations can giverise to a phase transition – specifically, to a quantumphase transition that occurs even at zero temperature.Quantum gas microscopes thus offer usthe chance to learn how the re-ordering of a systemtakes place during a phase transition, and on whattimescales. This is an unparalleled glimpse into theinner workings and dynamics of many-body systems,and one that would simply not be possible in thisdetail for a real material.In addition to using the phenomenal spatial resolutionof quantum gas microscopes to observe singleatoms, one can also perform other experiments.boptical latticelaser beamsa b cAtoms in a Bose–Einstein condensate (BEC) can be described by one macroscopicwavefunction, but at the same time a BEC in a lattice exhibits large fluctuations in thenumber of atoms per lattice site, n, thanks to an uncertainty-like relationship between n andthe wavefunction phase Φ (Δn ΔΦ > 1). In contrast, if the atoms are in a different phase ofmatter, known as a Mott insulator, strong repulsive interactions between the atoms destroythe coherent matter-wave field of the BEC, but they also suppress fluctuations in particlenumber. The result is an almost perfect ordering of atoms in the lattice, with one atomoccupying every lattice site.(a) Reconstructed atom positions in a BEC and (b–c) strongly interacting Mottinsulators. The hole in c actually corresponds to a region where two atoms are occupyingevery central lattice site. This region appears dark because the presence of near-resonantlaser light induces interactions between pairs of atoms trapped in the same lattice site,causing both atoms in the pair to escape the lattice. Hence, bright areas in the imagescorrespond to odd-numbered lattice occupancies.Nature 467 68; reused with permissionI Bloch, MPQPhysics World March 2013 49

Quantum frontiers: Quantum simulationphysicsworld.com3 Controlling single spins in an optical latticeaaddressing laser beammicrowave6.8 GHzbI Bloch, MPQyx2 μmcyxatoms in 2D optical lattice(a) Controlling the spins of atoms in an optical lattice requires a laser beam to “address” the atoms as well as a microwave field. When this addressing laser beam isfocused onto a single atom, it shifts the frequency of a transition between two spin states of the atom. If the frequency of the microwave field is set so that it isresonant with this shifted transition frequency, only the addressed atoms will have their spins flipped when the field is applied. By moving the addressing beam todifferent lattice sites, arbitrary spin patterns at the single-spin level can be prepared (b–c). Such precise control of spin patterns is a crucial first step to a number ofinteresting experiments, including the creation of a practical, scalable quantum computer using ultracold atoms.For example, if we send a laser beam in the reversedirection through the high-resolution microscopeobjective, we can focus the beam onto single sites ofthe lattice and selectively flip the spin states of eachatom (in other words, between different hyperfinespin states) in the microscopic array. By moving thebeam along a controlled pathway, an arbitrary spinpattern can thereby be imprinted onto the gases.The spin-flipped atoms can be made visible by firstremoving the unaffected (non-addressed) atomsand then imaging the remaining (addressed) ones.Examples of such single-atom spin orderings can beseen in figure 3. Once these spin patterns have beenprepared, they could form the initial conditions forobserving interesting non-equilibrium dynamics.For example, one can track the motion of a singleparticleimpurity in the many-body system, observethe dynamics of domain walls between regions ofdifferent magnetization, or track the collision of twospins at energies of a few pico-electron volts. Thepossibilities for interesting configurations abound.Artificial fieldsAnother condensed-matter problem that ultracoldatomresearchers have long wanted to simulate concernsthe effect of a magnetic field on the electronsin a 2D electron gas. For a single electron moving infree space, the presence of a magnetic field with acomponent perpendicular to the electron’s directionof motion creates a Lorentz force that pulls the electroninto a circular “cyclotron” orbit. If the electronis instead moving through a conductor, this sameLorentz force produces a voltage difference acrossthe conductor – the Hall effect. But when a 2D electrongas in a very pure semiconductor at very lowtemperatures is exposed to a magnetic field, somethingmore dramatic can happen: the Hall effectbecomes a quantum phenomenon, with the conductancein the semiconductor equal to ν e 2 /h. The coefficientν can take either integer or fractional values,and the fractional quantum Hall effect, in particular,remains a hot topic in condensed-matter researchmore than 30 years after its discovery. However, asevere problem exists in trying to simulate such physicswith ultracold atomic gases: because atoms areneutral, they do not experience any Lorentz force ina magnetic field. One might expect that this wouldprevent quantum-Hall-type effects from being realizedin an ultracold-atom system, but in fact theremay be a way around this problem.To understand how we might overcome such anapparently fundamental difficulty, let us take a closerlook at what, on a quantum-mechanical level, theeffect of a magnetic field, B, on a charged particlereally is. When an electron encircles an area with anenclosed magnetic flux, its wavefunction acquires aphase shift. This is known as the Aharonov–Bohmphase, and its value is given by φ AB = 2π Φ/Φ 0 whereΦ is the flux enclosed in the trajectory of the electronand Φ 0 , the magnetic flux quantum, is equal to theratio of Planck’s constant to the charge on an electron.The quantum-mechanical effect of the mag-50Physics World March 2013

physicsworld.comThis is an unparalleledglimpse into the innerworkings and dynamics ofmany-body systemsQuantum frontiers: Quantum simulation4 Realization of artificial magnetic fieldsaBe iφ 1φe –e iφ ABe –iφ 2netic field on the electron is thus to introduce a phaseshift φ on a closed-loop trajectory. Hence, if we areable to engineer such a phase shift in the wavefunctionof a neutral atom by other means, we will havesimulated essentially the same effect.Several possibilities have been outlined for doingthis using quantum optical control techniques. Onecan, for example, engineer a Hamiltonian such thatwhen an atom, initially prepared in a single quantumstate, is moved slowly in space in a way that does notinduce heating (adiabatically), no quantum jumpsto other energy levels occur. For a suitable choiceof Hamiltonian, the particle can pick up a phaseduring this state evolution – the so-called Berry’sphase – which depends on the geometric propertiesof the Hamiltonian. The Berry’s phase acquiredin this adiabatic state evolution then formally correspondsto the Aharonov–Bohm phase shift of acharged particle.Another possibility is to use laser-assisted hoppingof particles in an optical lattice to achieve thesame net phase shift. Imagine two neighbouring latticesites that are shifted in energy relative to eachother, such that a single particle cannot move tothe next site without some additional help, owing toenergy conservation. Laser light tuned to the rightfrequency can provide this missing energy, allowingthe particle to hop to the next site. Crucially, duringthis hopping process, the matter wave of the atomsinherits the phase of the optical wave. Laser-assistedhopping thus allows one to tune almost at will thephase shift produced when an atom hops from onelattice site to the next, and to render this phase shiftposition-dependent. For example, an atom hoppingaround a 2 × 2 plaquette in a lattice (figure 4) thuspicks up a phase shift of φ = φ 1 –φ 2 corresponding tothe Aharonov–Bohm phase shift an electron wouldpick up when hopping around a lattice plaquettewhile being exposed to a magnetic field.The interesting thing about this second possibilityis that in real materials, the achieved phase shift islimited by the strength of the applied magnetic fieldand is typically small. For ultracold atoms, however,such phase shifts can be tuned to any value betweenφ = 0 and π. In a real material, one would need toapply a magnetic field of several thousands of tesla –some two orders of magnitude greater than the fieldsgenerated by today’s strongest research magnets – toachieve the same effect. How will matter behaveunder such extreme field strengths? The answer isthat we don’t really know – we cannot calculate it,which is why it is worth doing the simulations. Sometheorists have predicted that one might encounterstates that are closely related to those of the fractionalquantum Hall effect in 2D electron gases.However, there is also real potential for discoveringnew phases of matter.As you might imagine, there are plenty of pathwaysahead for future research. One possibility wouldbe to extend high-resolution imaging techniquesto fermionic atoms, or even to polar molecules,which have strong electric dipole moments that giverise to long-range interactions. Being able to studysuch interactions at high resolution might bring anintriguing new perspective to our understanding ofquantum matter. Topological phases of matter withnew forms of excitations, such as Majorana fermions– an elusive particle that is its own anti-particle, andhas only recently been discovered in a condensedmattersetting – could be realized and probed withultracold atoms.Another fundamental topic that is currently muchdebated concerns how isolated quantum systemscome into thermal equilibrium; more specifically,it would be interesting to know which observablesshow thermal-like behaviour after a certain evolutiontime. Being able to probe, with high spatialresolution, how non-local correlations in the systemevolve in time would offer an exciting new way tounravel the secrets of these dynamics. One can onlyspeculate, but I am sure Feynman would have beenfascinated to see how far we have come in realizinghis vision of a quantum simulator and the possibilitiesit offers for future research.nMore about: Quantum simulation2012 Nature Physics Insight: Quantum simulation NaturePhys. 8 263J Dalibard, F Gerbier, G Juzeliu − nas and P Öhberg 2011Colloquium: Artificial gauge potentials for neutral atomsRev. Mod. Phys. 83 1523R P Feynman 1982 Simulating physics with computers Int. J.Theor. Phys. 21 467D Jaksch and P Zoller 2005 The cold atoms Hubbard toolboxAnn. Phys. 315 52b(a) An electron in a magnetic field B experiences a phase shift φ AB caused by the Aharonov–Bohm effect as it traverses a closed loop. (b) A similar phase shift can be achieved forneutral atoms in an optical lattice by using a laser to make them “hop” around a 2 × 2 regionof the lattice. Each hop along the x-direction imprints a phase shift φ i that depends on they-position of the particle. The net phase shift of the neutral atom hopping around the closedpath shown is then given by φ = φ 1 – φ 2 , corresponding to an “effective magnetic field”.yxPhysics World March 2013 51

Quantum frontiers: Communication in spacephysicsworld.comThe quantum space raceSending satellites equipped with quantum technologies into space will be the first step towards aglobal quantum-communication network. As Thomas Jennewein and Brendon Higgins explain, thesesystems will also enable physicists to test fundamental physics in new regimesThomas Jenneweinand BrendonHiggins are at theInstitute forQuantum Computingat the University ofWaterloo, Canada,e-mail thomas.jennewein@uwaterloo.caSuppose you have a photon – a single particle oflight. This is a quantum system by nature, so itexists in a particular quantum state. The photoncould, for example, be vertically polarized, horizontallypolarized or even something in-between: aquantum superposition.So what happens when you send your photon toa receiver at some other location? This questionsounds simple but the answer can tell us some quitefundamental and startling truths about nature. Infact, when a pair of photons possesses correlationsmuch stronger than classically allowed – entangledquantum states – the implications of what we observein so-called “Bell tests” are enough to have spookedeven Albert Einstein, and many people thereafter.The consequences of these experimental and theoreticalinsights are profound as they conflict withour intuitive understanding of how the world works(see box on p54). As Richard Feynman wryly concluded:“after people read [Einstein’s paper on relativity],a lot of people understood [it] in some way orother, certainly more than 12. On the other hand,I think I can safely say that nobody understandsquantum mechanics”.Beyond these fundamental interests is the field ofquantum communication – the science of transmittingquantum states from one place to another. Informationis often transmitted by using the aforementionedvertically polarized light to represent the “0”, horizontallypolarized to represent the “1” and a quantumsuperposition to represent a combination of “0”and “1” simultaneously. Quantum communicationhas received significant attention in the last few yearsowing to the discovery of quantum cryptography.Quantum-assured securityQuantum cryptography, or, more correctly, quantumkey distribution (QKD), exploits the fundamentalnature of quantum systems to change stateupon measurement, allowing you to establish a commonencryption key between yourself and a distantpartner with the absolute certainty that if someoneis eavesdropping, you will know about it. An eavesdropperwould leave a trace and, if none is found, thekey can be safely used to securely encode messages.These messages are sent using ordinary, classicalcommunication channels, before being decoded bythe distant party using their copy of the key. Traditionalencryption techniques, in contrast, either relyon assumptions that certain mathematical operationsare difficult to invert, or require the effort of atrusted courier to physically carry the key from onelocation to the other.Because of this obvious and significant application,it is not just researchers tucked away in universitylaboratories who are interested. Severalquantum-communication companies have alsoemerged over the last few years seeking to exploitthe secure messaging that QKD allows, includingID Quantique in Switzerland, MagiQ in the US andQuintessenceLabs in Australia. Their efforts comeon top of established programmes by the likes of HP,IBM, Mitsubishi, NEC, NTT and Toshiba. All ofthese companies – and more – are looking to developreal-world-applicable QKD devices for governments,banks and other security-focused clients.The devices that are being built and implementedtoday form the seeds of what could one day becomea grander quantum internet – interconnected networksof quantum-communication channels. Thesenetworks would permit not just quantum-securedcommunications, but also distributed quantum computation(several quantum computers working onthe same problem in tandem) and other quantumenhancedinformation technologies.While the possibilities are exciting, quantum communicationover long distances turns out to be reallydifficult. The culprit: transmission loss. Signalsweaken in intensity when they travel long distancesbecause photons get absorbed or scatter off molecules,with the transmission loss getting exponentiallyworse with distance. Classical communicationcan cope with the high losses experienced over longdistances by using repeater devices to boost the signal.But for quantum signals this approach does notwork. Quantum signals cannot be perfectly cloned,which rules out standard repeaters, and tricks such asboosting the signals by transmitting many duplicatesof each quantum state at the same time would defeatthe purpose of encoding information into individualquantum systems in the first place: an eavesdroppercould simply pick off and examine a subset ofthose duplicates, which outwardly would appear tobe nothing more than regular loss. As it stands, thefurthest that quantum-communication signals havebeen sent is only a few hundred kilometres.For applications such as quantum cryptography,that distance restriction means that your QKD systemcan at best allow you to securely communicatewith someone just one or two cities away, which ishardly ideal in an increasingly globalized society.Moreover, in terms of physics research, it means that52Physics World March 2013

physicsworld.comQuantum frontiers: Communication in spaceGemini Observatoryimportant theories can only be verified by experimentaltests up to a few hundred kilometres. Frustratingly,some of the proposed effects from theinterplay of quantum mechanics and relativity wouldbe too subtle to measure on this scale. So until wecan somehow surpass the tyranny of distance, suchnew physics cannot be tested at all.Into the voidFortunately for anyone involved in quantum communication,there is one environment where scatteringhappens to be practically absent over a very long distance:empty space.The near-vacuum environment beyond Earth’satmosphere is ideal for low-loss optical transmission;optical diffraction is the only transmission loss worthconsidering. So an obvious next step to take quantumcommunication beyond its terrestrial limitationsis to deploy a satellite fitted with a transmitter and/orreceiver that can implement quantum tasks such asQKD. As a bonus, this equipment could be used tolook at fundamental questions within quantum physicsin a regime that has never before been explored.The first step towards space-based quantum communicationwould be to place a satellite in a low-Earthorbit (LEO) – i.e. at an altitude of less than 2000 km.While a satellite in LEO can see only a small area ofthe Earth’s surface at once, it moves with a relativelyhigh orbital velocity of about 8 km/s, which ensuresthat its coverage includes all of the Earth at different,Photons in spaceQuantumcommunicationbetween a groundstation and asatellite in spacecould looksomething like thislaser guide starsystem at the GeminiNorth Observatoryin Hawaii.Physics World March 2013 53

Quantum frontiers: Communication in spacephysicsworld.comBell testsOne of the most perplexing properties of quantum mechanics, entanglement isa special case of quantum superposition in which two or more particles havequantum states that are so correlated with each other they cannot be explainedas separate entities. Take, for example, the so-called “singlet” state of twophotons. When the polarization of one of the photons in this entangled stateis measured, the result (“0” or “1”) instantly tells us that the other particle willbe found in the opposite state, even though we cannot predict beforehand inwhich state either photon will be found. Remarkably, it does not matter whichmeasurement we perform – it is always the case that we know, instantly and withcertainty, that the same measurement done subsequently on the second particlewill produce the opposite outcome.Albert Einstein, Boris Podolsky and Nathan Rosen famously thought about thisstrange behaviour in 1935, and concluded that if quantum mechanics is right,then it must violate at least one of two intuitive notions about the fundamentalphysical world – locality and realism. Locality dictates that cause and effectcannot travel faster than the speed of light (as per Einstein’s relativity), whilerealism states that particles have well-defined properties whether they aremeasured or not. If one assumes the latter, then the entangled photons mustsomehow achieve superluminal communication such that the measurement resultfrom one photon is transmitted instantly to update the state of the second.However, the perfect correlations considered in such theoretical treatmentscannot be tested by experiments, because any experimental set-up hasimperfections. For decades it was presumed that the theoretical preconceptionsheld true, and quantum theory was somehow incomplete. It was not until thescenario was put into quantitative terms by the Northern Irish physicist John Bellthat the possibility of experimental tests became apparent. He deduced thatstatistical analysis of the results of various measurements of each photon wouldyield a parameter that must be less than a certain value if the world followedlocality and realism. Put into mathematical terms, Bell produced an inequalitythat the pair of classical preconceptions would never violate; but quantummechanics, in principle and with sufficiently pure entangled systems, could.In the almost five decades since Bell derived his eponymous inequality,experimental tests have, with increasing certainty, demonstrated that the jointassumption of locality and realism cannot be maintained – at least one of thosemust be incorrect. While work continues on Earth to finally close the variousexperimental loopholes all at once, the prospect of performing Bell tests usinga quantum satellite raises the possibility of addressing new questions, includinghow well quantum mechanics holds over extreme distances, and the possibleinterplay of gravitation.sometimes multiple, times in a single day.In contrast, a satellite in a geosynchronous orbit(GSO) sits at an altitude of about 32 000 km, allowingcoverage of almost 50% of the planet at alltimes, which means quick or even simultaneousQKD. But implementing a GSO system is more difficultand costly because such an orbit is necessarilymuch higher than LEO. GSO is therefore moreof a long-term goal, perhaps once the economics ofsatellite-based quantum communication makes suchan investment commercially viable. In this scenario,one could envision a constellation of quantum satellites,with several satellites communicating with eachother and orbiting in a pattern that simultaneouslycovers all of the Earth, thereby expanding the futurequantum internet to the global scale.Whichever satellite arrangement is used, its purposeis to act as a kind of relay between two groundstations in a way that allows them to establish asecure link. This link could be accomplished in a fewdifferent ways (see box opposite).Fundamental science in spaceSeveral untested theories detail subtle effects thatquantum states might experience over the distances,velocities and gravitation that a quantum-satelliteplatform could achieve. In fact, there is abundantfundamental physics at the intersection of quantummechanics and general relativity that has never beentested, simply because we have never before hadaccess to the relevant regimes. A quantum satellitewould allow us to take the first step in testing theoriesover large distances, at high relative speeds andunder varying gravity.Consider this example: if a pair of entangled photonsis prepared at some source location, split andthen sent to two observers, the first observer tomake a measurement will find one state, instantlydetermining in which state the other particle willbe found when measured by the second observer.Special relativity, however, causes a complicationin the cause-and-effect picture that we intuit: if theobservers are some distance apart and moving awayfrom each other, relativity dictates that this motionwill influence the timing of the measurement events,depending on which observer you consider. In certainconditions, such as if both observers are equidistantfrom the source, both observers will concludethat their measurement was the second one, the firstbeing done at the other platform. This presents atricky puzzle for common interpretations of quantumentanglement, where the outcome of the secondmeasurement is determined at the instant thefirst measurement produces a result. The puzzlingquestion is at what point the outcome is determined,when the time-order of measurement events dependson which observer asks the question.One of the hopes of investigating such questionsis to finally bring the famously incompatible quantumand relativity theories to a truce, or somethinglike it. Quantum theory (describing the behavioursof the very small) and relativity theory (describingthe behaviour of the very large) have both been thoroughlydemonstrated to be the most accurate and precisemodels of the physical world, to the extent of theirapplicable regimes, that humankind has ever devised.Their incompatibility is almost embarrassing.Scientific experiments performed within newregimes have historically led to significant advancementsof our knowledge and understanding of theinner workings of the universe. At present, humanity’sdata set of quantum knowledge comes from testswith maximum distances of hundreds of kilometresand maximum speeds of hundreds of kilometres perhour. In comparison, a LEO satellite would allow usto reach maximum distances of about 1000 km andspeeds in the tens of thousands of kilometres perhour, enabling us to test a litany of potential effectsand quantum behaviours that cannot be achieved onthe ground.The most clear-cut example to study is longdistancequantum entanglement, including verifyingentanglement between photon pairs spanning Earthand space, checking how the quality of entanglementmeasurements scales with distance, as well as examiningthe effects of special relativity on entangled sys-54Physics World March 2013

ABphysicsworld.comQuantum frontiers: Communication in spaceTowards global quantum communicationEarthQKD at time t 1QKD at time t 2QKDABABEarthGlobal communication, such as fibre-optic broadband, couldbe made more robust by establishing a secure encryptionkey between two communicators that no-one else couldpossibly know. This could be done by using a satelliteenabled with quantum technologies to act as a kind of relaybetween two ground stations to establish a secure key.One way of doing this would be a “trusted QKD node” approach(left), in which an orbiting satellite first establishes a key –key 1 – with station A via quantum key distribution (QKD),sending single photons one at a time either by uplink (fromground to satellite) or downlink (from satellite to ground). Thesatellite travels some Adistance and then B establishes another,different, key – key 2 – with station B. (QKD itself cannottransmit existing keys, but only generate new ones.) Thesatellite then encodes key 1 with key 2 (encrypting it) andtransmits the result over radio communications to groundstation B, which uses the key Earth it knows (key 2) to determinekey 1. At this point both ground stations possess a sharedsecure key – key 1 – which enables them to communicatesecurely on the ground via the usual classical means.This approach comes with a caveat, however: the satelliteknows the secure key that the ground stations will use. If anefarious entity were to somehow penetrate the security ofthe satellite, which would be no small feat given a properlydesigned autonomous orbiter, then the security of thecommunication on the ground would be vulnerable. One hasEarthto trust that the satellite is secure.Fortunately, it is possible to utilize a different approachsuch that the satellite can act as an “untrusted node” (right).Here, an orbiting satellite generates entangled photonpairs and transmits one photon of the pair to each of theground stations A and B simultaneously. The entanglementcorrelations between the photon pairs allow A and B toextract a common secret key that even the satellite doesnot know. The ground stations could then compare theirdetection statistics, independent of the source, in a mannersimilar to a Bell test (see box opposite), allowing them toverify that no other party gained information about thestates they received – not even the satellite. (Anotherproposal reverses this idea, with each ground stationgenerating and transmitting single photons that are receivedand entangled by the satellite, although this is considerablymore technically challenging.)Verification of the trustworthiness of the source meansthat no assumptions have to be made about the security ofthe satellite, but it does mean that the satellite needs muchmore complex kit, including an entangled photon source andtwo telescopes that can be pointed independently. Theseextra complications make the trusted node, by comparison,seem like a good stepping stone for testing quantumencryption with a satellite, moving towards an untrustednode approach as a long-term solution.tems (including the moving observers scenario above).Moreover, long-distance “quantum teleportation”experiments could be conducted – the first baby stepstowards realizing the famous Star Trek “Beam me up,Scotty” command may be only a few years away.Meanwhile, back on Earth...For these experiments to be conducted any time soon,an actual design for a satellite must be nailed downand, of course, built. As for anything of a space-faringpedigree, this encompasses a number of technicalchallenges that need to be resolved. First and foremostis figuring out how to successfully transmit thequantum optical signal between the satellite and theground station, which has been studied in increasingdetail by various groups worldwide. The problemthat needs to be overcome is atmospheric loss – notin space, but in the region near the ground station.Other effects to contend with include atmosphericturbulence, diffraction and background noise. Ourown group at the Institute for Quantum Computing(IQC) in Waterloo, Canada, has recently concludeda comprehensive theoretical study, simultaneouslyincorporating all of the significant effects on the signalthroughput, which has helped us to determine whatoverall design features of the satellite and ground stationsystems would be suitable. We also calculated theexpected performance of the quantum optical signalfor QKD and fundamental science endeavours.Another important technical challenge is to ensurethat the quantum channel between the satellite andthe ground station is precisely aligned as we needThe puzzlingquestion isat what pointthe outcomeis determined,when thetime-order ofmeasurementeventsdepends onwhich observerasks thequestionPhysics World March 2013 55

Quantum frontiers: Communication in spacephysicsworld.comIQCNo small ambitionThomas Jennewein(pictured) is leadingan effort to designand implement aquantumcommunicationsatellite, a miniaturemodel of which isshown here.to be certain that what we actually measure correspondsto the photon states that were prepared. Thismeans that as well as accurately pointing the transmitterand receiver at each other, timing and opticalpolarization must be well aligned. What makesthings even more complex is that the satellite changesposition as it passes overhead, so the time delay andlocal polarization frame are constantly changing.The Global Positioning System (GPS) can give ustiming accuracy down to 100 ns, but this will not beenough to accurately identify which of the detectedphotons are from the transmitted photon stream –and where within that stream they originate – ratherthan from some source of background noise. Experimentswill be performed at night to minimize lightnoise, but even then there is noise inherent to thedetectors, which can unintentionally “click” even inthe absence of a photon. To go beyond GPS capabilitywill require additional techniques such as highprecisiontime-tagging of photon detections, pulsing“beacon lasers” according to a known pseudo-randomsequence to which the transmitter and receiver cansynchronize, and advanced post-processing.Aligning the photons’ polarization frame with thatof the detector also requires some thought – for goodperformance, these have to be within about 5° of eachother. Again, GPS can help here, providing measurementsof position and orientation that can be usedto determine the correct compensation to apply. Forsome designs, the satellite could be rotated slowly asit passes over a ground station so that its polarizationframe lines up with that on the ground. On-the-flycalibration could be done using a polarized beacon,whereby the receiver measures the polarization ofthe beacon and then aligns itself with that either bychanging its physical orientation or by using an opticalelement. One other potential alignment methodthat we are studying at the IQC is based on analysisof the quantum signal itself.While designing this innovative equipment, partof which we plan to send into space, we must continuallykeep in mind the more mundane physicalconstraints that we face: mass and power. We cannotexpect the satellite on which we choose to houseour quantum payload to carry up too much mass, orto provide too much power once it is in orbit. Manypotential space-faring groups intend to install theirequipment on a microsatellite, upon which mass andpower are at a premium. Fortunately, designs of systemswith the necessary low mass, that use low powerand embedded hardware, are making rapid progress.Quantum space raceSeveral research groups are pursuing the concept ofa quantum satellite in friendly competition. RichardHughes’ group at Los Alamos National Laboratory inthe US has been pioneering aspects of QKD on spaceplatforms for many years, and NASA has recentlyindicated renewed interest. Anton Zeilinger’s groupat the University of Vienna in Austria has beenworking with the European Space Agency for severalyears towards deploying an entangled quantumtransmitter on the International Space Station.Jian-Wei Pan’s group at the University of Scienceand Technology of China in Hefei has been makingconsiderable progress, with recent proof-of-conceptexperiments and a proposed launch date of 2016.Meanwhile, Alexander Ling’s group at the NationalUniversity of Singapore is preparing to launch asmall “CubeSat” with an enclosed entangled photonsource on board. Last but not least, researchers atthe National Institute of Information and CommunicationsTechnology, Koganei, Japan, are developingtheir own QKD satellite demonstration.At the IQC we are working closely with the CanadianSpace Agency and industry partners to designa quantum satellite. The approach we are pursuingfavours using the quantum receiver as the satellitepayload, i.e. a trusted node in an “uplink” configuration(see box on p55). Compared with a “downlink”with a satellite transmitter, this configuration suffersfrom more photons being lost as a result of atmosphericturbulence causing the beam to slightly deviateearlier in the transmission, thus having a strongereffect on pointing losses. This reduces the rate atwhich a quantum key could be generated becausethe loss hampering the photon transmission reducesour quantum-communication bandwidth. However,there are many advantages of an uplink: a quantumreceiver apparatus is quite simple, robust and standardizedas compared with a quantum transmitter;and a ground transmitter means that different quantumsource designs can be easily utilized wheneverit is appropriate.We are currently carrying out design-feasibilityassessments in the laboratory, weeding out anypotential problems before an actual satellite is builtand sent into orbit. While it is not clear yet whichgroup will be the first to get a fully working quantumcommunicationplatform into space, current progressis very promising. With the prospect of globalscalequantum communications and fundamentalquantum science within new, unexplored regimes,the next few years are sure to be exciting. To boldlyquantum where no-one has quantumed before. n56Physics World March 2013

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physicsworld.comReviewsLowry KirkbyA physics primer, with equationsLinda A Cicero/Stanford News ServiceThirst for physicsLeonard Susskind’spopular series oflectures for thegeneral public havebeen compiled inthis book.The TheoreticalMinimum: What YouNeed to Know toStart Doing PhysicsLeonard Susskindand GeorgeHrabovsky2013 Basic Books£20.00/$26.99hb256ppThe mantra for popular-sciencebooks is to minimize the use ofequations. In The Theoretical Minimum:What You Need to Know toStart Doing Physics, authors LeonardSusskind and George Hrabovskyhave taken the opposite approach byproducing a physics book for the educatedgeneral public that emphasizesthe mathematics needed to solvephysics problems.When I first heard about the premiseof the book, I was intrigued. Isthere a group of people who want tosolve physics and mathematics problems,and not simply read about thegee-whiz physics that is the standardfare of most popular-science books?To my surprise, apparently there is.The Theoretical Minimum is the productof a series of lectures that Susskindpresented for the general publicin the Stanford area – all of whichcan be found video-recorded on theWeb – and these lectures attracted alarge following of people who were,in Susskind’s words “hungry to learnphysics”. Indeed, Hrabovsky himselfwas one of those people. Now presidentof the Madison Area Scienceand Technology organization, whichis devoted to research and education,Hrabovsky has no formal scientifictraining but taught himself physicsand mathematics – presumablythrough courses and books similarto The Theoretical Minimum.This thirst for academic learningoutside of a conventional universitydegree reminded me of therecent and rapid growth of so-calledmassive open online courses, orMOOCs: open-access (i.e. free) universitycourses that give people ofany age or background the chanceto learn about a subject that intereststhem, at their own pace (see p9).Like MOOCs, The Theoretical Minimumallows knowledge-lovers to gettheir teeth into the kind of physicsand mathematics problems that onewould normally face during a universitydegree. As Susskind puts it,it is intended for “people who oncewanted to study physics, but life gotin the way”.The book is written in the formof 11 short lectures that cover classicalmechanics, plus a final chapteron electromagnetism. Thoughreplete with equations, it remainsvery readable. Abstract concepts arewell explained, usually in a coupleof different ways to give the readera good conceptual overview of theprinciple at hand. For example, onedoes not need to understand everydetail of a given equation in orderto comprehend its power and its use,since these are explained in the text.In addition, each lecture includesseveral exercises, allowing readersto put their problem-solving skillsinto practice. (Solutions to the exercisesare posted on the Web.) Thefirst three chapters include mathematicalinterludes on trigonometry,vector notation, differentiation andintegration. These discussions arecomplete, and would serve as a goodreminder for someone who is alreadyfamiliar with calculus; however, theyare also rather terse, and would likelybe too advanced for someone whowishes to learn it for the first time.Is this really just the minimumyou need to know to start doingphysics? To me, the answer is anemphatic “no”: this book covers farmore than the minimum. The firstfive chapters cover the core classicalmechanics principles of motion anddynamics, including conservation ofenergy and momentum, while thematerial covered in the second halfof the book (chapters 6–12) is usuallyconsidered “advanced classicalmechanics”. This material – whichincludes Lagrangian and Hamiltonianmechanics and their applicationsto electric and magnetic forces– is often not taught at undergradu-Physics World March 2013 59

Reviewsphysicsworld.comate level in the UK since it is not partof the Core of Physics syllabus issuedby the Institute of Physics. Indeed, Idid not cover these subjects duringmy undergraduate physics degree atthe University of Oxford. As such,I can attest to the readability of thebook: I was able to understand whatan equation that I had never seenbefore represents, without havingto pick apart and understand everyterm that makes it up. In fact, I foundit satisfying to finally gain a basicunderstanding of Lagrangian andHamiltonian mechanics, since I hadsometimes wished we had coveredthese subjects in my degree. I evenfelt like I had been partially dupedduring my degree after readingSusskind’s comment that the Euler–Lagrange equations comprise “all ofclassical physics in a nutshell”!There is, however, a flip side to mysatisfaction at filling in some holesleft by my undergraduate degree: Ifound myself wondering how muchsomeone who has not had formalmathematics or physics trainingwould really get out of The TheoreticalMinimum. The concepts presentedin it are not only advanced,but also abstract and unintuitive,Next monthin Physics WorldBlow to the headHow physical impacts from bomb blasts and in contactsports can cause disturbing long-term brain injuries onthe battlefield and the playing fieldI found itsatisfying tofinally gain abasicunderstanding ofLagrangian andHamiltonianmechanicsand I would imagine they would bequite daunting to someone new tothe subject. At the very least, theywould leave newcomers scratchingtheir heads. The book is reallyabout explaining mathematics andabstract physics and does very littleto relate these concepts back toeveryday life. In addition, in manyinstances I thought that the explanationwould benefit from a diagramor two. Susskind is one of the fathersof string theory, arguably one of themost abstract and theoretical areasof physics. However, the rest of usare not: we need a more tangible wayto learn.In summary, although this bookprobably offers more than manyreaders will have bargained for, itdoes provide a clear description ofadvanced classical physics concepts,and gives readers who want a challengethe opportunity to exercisetheir brain in new ways. Thanks tothe breadth of accompanying information(for example, exercises andvideo-recorded lectures on the Web),it also enables them to learn at theirown pace, and hopefully most willget some fun and satisfaction fromit. If members of the general publicreally are pulling for these typesof courses, ones that offer rigourand a challenge, I enthusiasticallyencourage them.Lowry Kirkby is a PhD student in biophysicsat the University of California, Berkeley, US,and the author of Physics: a StudentCompanion (2011 Scion Publishing), e-maillowry.kirkby@berkeley.eduShutterstock/Richard Paul KaneDetangling DNA60 years on from the discovery of DNA, researchersare finding that the incredibly complex knots these longmolecules form – and the mechanisms by which theseknots untangle – can be understood in terms of topologyDealing with demonsJames Clerk Maxwell’s fictional demon was devisedas a thought experiment, but some of the physicist’scontemporaries actually believed it was an intelligentbeing that could shine a scientific light on the human soulPlus News & Analysis, Forum, Critical Point, Feedback,Reviews, Careers and much morephysicsworld.com60Physics World March 2013

physicsworld.comReviewsWeb life: The Quantum ExchangeURL: www.thequantumexchange.orgSo what is the site about?The Quantum Exchange describes itself as “aWeb-based repository of resources for teachers ofquantum mechanics and modern physics”. It is, ineffect, a one-stop shop for visual aids, interactivetools and supplementary information designedto help undergraduates – and, for that matter,anyone else with a serious interest in learningmore about the quantum world – understandthe physics of wavefunctions, probability, spin,entanglement and other quantum fundamentals.What sorts of resources are included?Videos of lectures by notable quantum physicists,Mathematica notebooks on energy eigenstatesand Java applets that simulate wavefunctionevolution all feature in the site’s extensivearchive. So do a few oddities, such as a fiendishlytricky quantum version of Tic Tac Toe (that’s“noughts and crosses” in UK English). Many of theresources seem designed to slot into a traditionallecture-based quantum mechanics course, butothers are more open-ended, and would be bestused in laboratory or tutorial sessions.Can you give some specific examples?One of the most interesting resources in therepository is the Friedrich-Alexander-UniversitätErlangen-Nürnberg’s QuantumLab, which takesan unusually practical approach to explainingconcepts such as quantum randomness,entanglement and cryptography. Rather thanrelying solely on diagrams, QuantumLab usesphotographs of actual optical layouts andinteractive widgets that enable students to findout what happens if (to take just one example)they change the polarization of a laser beamas it passes through various optical elements.Students who have access to an optics lab willbe able to reproduce these layouts (and thusWho is behind it?The site was developed by the AmericanAssociation of Physics Teachers with fundingfrom the US National Science Foundation, and iscurrently managed by Bruce Mason, a physicistand educator at the University of Oklahoma. It is,however, international in its scope, with links to(mostly) English-language resources created byphysicists in France, Germany, Austria and theEurophysic_125x193:MiseNetherlands as well as the US andenUK.page 1 11/09/12the experiments)16:56withoutPagetoo1much difficulty; forthose who lack the right array of lasers, beamsplitters and so on, a site like this is surely thenext best thing. The Quantum Exchange alsoincludes up-to-date links to some excellent olderresources, such as the pages on laser coolingand Bose–Einstein condensation developed byphysics educators at the University of Colorado inthe early 2000s. Like any Web repository, it doescontain a few links to resources that no longerexist, but not enough to make it frustrating.Why should I visit?There are a lot of Internet resources that aredesigned to help teachers, students andmembers of the public understand and explore allmanner of quantum phenomena – ranging fromclassic problems such as the “particle in a box”to the sort of cutting-edge research discussed inthis special issue of Physics World. The principaldifficulty lies in finding the right resource for aparticular situation. By combining the efforts ofmany educators, research groups and outreachspecialists – each with their own strengths andweaknesses – into a single, searchable database,The Quantum Exchange makes this processeasier. Its centralized approach is also useful forwould-be developers of new resources, who cancheck it to make sure their cherished projects arenot reinventing someone else’s wheel.www.goodfellow.comMetalsand materialsfor researchGoodfellow Cambridge LimitedErmine Business ParkHuntingdon PE29 6WR UKTel: 0800 731 4653 or +44 1480 424 800Fax: 0800 328 7689 or +44 1480 424 900info@goodfellow.comON-LINE CATALOGUE70 000 PRODUCTS SMALL QUANTITIESFAST DELIVERYCUSTOM MADE ITEMSPhysics World March 2013 61

Reviewsphysicsworld.comArneroPhilip AndersonAn iconoclast’s careerIdeas manArtist’s concept ofDyson rings forminga stable Dysonswarm – just one ofmany diverse ideasto come fromFreeman Dyson.Maverick Genius:the PioneeringOdyssey ofFreeman DysonPhillip Schewe2013 Thomas DunneBooks £17.49/$27.99hb 352ppThe “maverick genius” referred to inthe title of Phillip Schewe’s book isFreeman Dyson: a truly great mathematicalphysicist, bestselling author,longest-serving member of the USmilitary’s JASON advisory group,and occupant of the “fourth chair”when the Nobel Prize for Physicswas awarded for quantum electrodynamics(QED) – among manyother distinctions. Indeed, a biographyof Dyson was long overdue, eventhough his own autobiographicalwritings are extensive and so beautifullywritten that no ordinary authorcould match them, Schewe included.Why, in that case, should webother with this biography? Because,as the author makes clear, there aremany Freeman Dysons, and howthey developed (evolved?) into eachother, and what their relationship is,are both relevant parts of his story –as is some kind of appraisal of whatone is to make of the final individual.My own contacts with Dyson havebeen indirect. Of course, I tried tounderstand the fundamental QEDpapers of 1949 that revised all ourviews of quantum field theory, andI used the techniques presented inthem to help solve a puzzle in solidstatephysics. Then, in 1958 I waschosen as a substitute for Dysonafter he was enticed away from theUniversity of California, Berkeley– where he had spent three summersresearching condensed-matterproblems with Charles Kittel – towork at General Atomics in La Jolla,California. There, for much moremoney than Kittel could command,Dyson helped design the safe reactorTRIGA and the Orion spaceship. (Ihad a marvellous summer at Berkeley,though my papers were crudecompared with Dyson’s.) But we didnot meet until the first energy crisis,when we both attended a workshopon energy that was sponsored by theAmerican Physical Society. Afterwards,we met at disarmament seminarsat Princeton University in NewJersey, which is where I first sensedhis ambiguity about conventionalliberal positions on subjects such asthe “Star Wars” defence initiative –most of which I hold unambiguously.This is not an authorized biography,so Schewe did not have accessto any private letters in his research.However, he is a well-known popularizerof physics (being employed in thatcapacity by the American Institute ofPhysics) and he has done a meticulousjob of finding all of the relevantsources available. He has researchedthe course of Dyson’s life in detail,beginning with his privileged andprecocious childhood at Winchesterand foreshortened Cambridgeyears, which were overshadowed bythe approach of the Second WorldWar. Dyson spent the war years doingoperations research for BomberCommand, and his determinedlyitinerant graduate years with HansBethe and Richard Feynman culminatedin the great breakthrough ofQED. After his relatively brief, butscientifically fertile, junior facultyyears at Birmingham and Cornell, hesettled permanently at the Institutefor Advanced Study (IAS) at Princetonin 1953, at the age of 30.“Settled”, however, is hardly theword for it: the liberal vacations andrelaxed leave policies of the IAShave enabled Dyson to become theepitome of the “have briefcase, willtravel” scientist, bringing him severalfurther careers. The one that seemedto leave the strongest impression onhim was his involvement with thenuclear world and particularly theOrion project, which foreshadowedmajor themes of his later career.Orion was a nuclear-powered spaceshipthat he, Edward Teller and TedTaylor designed in 1959 and advocatedthereafter, and this experienceseems to have left him with a visionarypredilection for thinking theunthinkable in terms of the long-termfuture of the human (or other intelligent)race in space. He also becamea major influence in the effort toachieve some measure of nucleardisarmament; after initially opposingthe test ban treaty, as a JASONconsultant he co-wrote an influentialreport opposing the employment ofnuclear weapons in Vietnam.Until the 1980s Dyson kept up acontinuous and active career in mathematicalphysics, with occasionalforays into broader interests such ascondensed matter, biology (particularlystudies on the origins of life) andastronomy. Around that time, he discoveredhis second métier as a writerof extraordinarily readable prose. Anumber of well-received essays werefollowed by his first autobiographicalbook, Disturbing the Universe (1979),which was nominated for the USNational Book Award. Then cameWeapons and Hope (1984), whichcaptured the public’s interest in theReagan administration’s StrategicDefense Initiative (the aforementioned“Star Wars”). He continuesto publish a book every few yearsas well as many articles and bookreviews. Partly thanks to his prolificwriting, but also because he seems to62Physics World March 2013

physicsworld.comReviewshave something inspiring and beautifullyphrased to say for any occasion,he has become a popular lecturerand maintains a frighteningly fulltravel schedule. Most recently hehas delighted in maintaining minorityviews on a number of topics suchas climate, religion (his Christianityplaces him in the minority for hisprofession) and genetic modification.Did he ever have time for a privatelife? Schewe’s book records Dyson’sclaim (perhaps a dubious one) tohave had two principles in his relationswith women: he did not allowhimself to become interested if hedidn’t have marriage in mind; andhe intended to have six children. Heproposed to his first wife, Verena– a bright, glamorous mathematicianand single mother at the IAS– almost on meeting her, and wooedher by mail for over a year throughouthis continual travels until (withsome reluctance on her part) theymarried in 1950. She bore him twochildren before a miscarriage, buttheirs was a somewhat stormy marriage,noteworthy for the fact that herthesis and mathematical notes weredeliberately burned in the interest ofdomesticity. Both children, Estherand George, became well-known figures,she as a journalist-entrepreneurand he as an author. Dyson’s secondwife Imme, formerly his children’s aupair, produced four more daughters.Friends of his children report thatDyson is a kindly, avuncular figure,though a rather strict father.A more important question,though, is whether Dyson is theimportant world figure that Schewemakes him out to be. In his career,we can see traces of the mathematicalphysicist’s reluctance to tacklethe ambiguous or deeply puzzlingquestion, or to go out mathematicallyeven a little bit on a limb – somethingthat contrasts sharply with his joyfulinterest in bizarre futurology. Perhapsthis is the source of Dyson’sdreadful misjudgment on the climatequestion: he sees that the possibleerrors are large, but does not factorin that they are likely to be large inthe wrong direction, and does notcredit obvious qualitative argumentsfrom simple laws of physics.One could wish, as in many biographiesof scientists, that the scientificcontributions were morecritically presented and contextualized.Sometimes the hype goestoo far, as when Schewe comparesDyson’s popularity as the guru ofQED in the 1950s with the Beatles’“conquest of America” in the 1960s.Dyson’s very elegant arguments donot always have much to say abouthow things work in the real world,and the author makes little effort todistinguish whether they do. He didnot, for one thing, participate in anyof the revolutionary events that createdthe Standard Model. However,my own preference is for the sloppyand practical rather than elegant andprecise, so I am prejudiced.It is natural for biographers to fall alittle in love with their subjects, but onbalance, this book leaves the readerintrigued but a bit unsatisfied. Dysonis a superbly able man and has doneso much, but what if he had focusedon one career? Perhaps the careerhe really wanted was scotched, asSchewe suggests, by the fallout problemsof Orion? In any case, he is worthreading about and marvelling at.Philip Anderson is a condensed-matterphysicist at Princeton University in the USwho has dabbled in complexity theory,astrophysics and even particle theory, e-mailpwa@princeton.eduParticipate at North America’slargest optical fabrication event.Call for PapersSubmit your abstract by 1 April 2013www.spie.org/ofb1Conference14–17 October 2013Exhibition15–17 October 2013LocationRochester RiversideConvention CenterRochester, New York, USACo-sponsored byUntitled-1 1 15/02/2013 09:19Physics World March 2013 63

Reviewsphysicsworld.comPrinceton University PressBetween the linesHidden messageThe cover of TheUniverse in ZeroWords cleverly hidesequations in theMilky Way.On beyond zeroThe Universe in Zero Words soundslike the title of a coffee-table bookof astronomy photos. The imageon its cover – a photograph of theMilky Way – does little to suggestotherwise. But the book DanaMackenzie has actually written isa very different beast indeed. Acloser look at that star-spangledcover reveals a host of equationsscattered through the night sky, andinside it is an elegantly illustratedhistory of mathematical thought,rather than a series of nebulaphotos. Mackenzie’s chronicle isimpressive in its scope, running allthe way from 1+1=2 (an expressionwith some surprisingly interestingproperties) through to 20th-centuryrevelations such as Lorenz’sequations of chaos theory and therealization that some infinities arebigger than others. Understandably,Mackenzie, a mathematicianturned-writer,uses rather morethan zero words to describe thesediscoveries: the book is dividedinto 24 semi-independent essays,each nominally based on a singleequation or group of equations.Most of these expressions will befamiliar to physicists, but thereare also a few oddities, such as theChern–Gauss–Bonnet equation,and even “old favourites” suchas Maxwell’s equations are oftenpresented with a fresh twist. Thistendency is apparent from the firstfew essays, which frequently givecredit to ancient mathematicianswho lived outside the Greco-Roman world of Euclid andArchimedes. In particular, anaccount of Liu Hui, a Chinesemathematician and commentatorfrom the third century AD, enlivensthe essay on the “Pythagorean”theorem – which, as Mackenziemakes clear, was not Pythagoras’invention, having been known tothe Babylonians for more than amillennium before Pythagorasstarted teaching in the 6th centuryBC. This cross-cultural focus isparticularly appropriate given thebook’s title, which refers to thePlatonist idea that numbers andequations express truths about theuniverse that are independent ofwords, language or culture. Whatwas that old proverb about booksand covers, again?●●2012 Princeton University Press£19.95/$27.95hb 224ppProof positiveProve that a parallelogram withequal diagonals must be a rectangle.Show that the surface area of asphere is exactly two-thirds thatof its (closed) cylinder. Derive theequation for a hyperbola. If theseinstructions induce puzzlement,a vague sense of “I used to knowhow to do that” or even a barelysuppressed twinge of panic, thenMeasurement deserves a placeon your shelf. Written by PaulLockhart, a New York-basedmathematics teacher and educationadvocate, the book aims not onlyto teach mathematics, but alsoto instil in readers a genuineappreciation for the subject andan understanding of why it isbeautiful and worth learning. Inhis introduction, Lockhart admitsthat this will not be an easy process;mathematics, he writes, is like ajungle, and “the jungle does notgive up its secrets easily…I don’tknow of any human activity asdemanding of one’s imagination,intuition and ingenuity”. On theother hand, mathematics is also“full of enchanting mysteries”,many of which are accessible even tonovices – provided they are willingto play around with ideas and alsodevelop a high tolerance for gettingstuck. To help readers build theirmathematical muscles, Lockhart haspeppered his book with questionsand puzzles like the ones thatopened this review. The solutions tosome of them are worked out (or atleast worked around) in the text, butmost are left as an exercise for thereader, without further commentor explanation from Lockhart. In aformal textbook, such an approachwould be frustrating – especiallyfor students with problem sets dueevery week, who seldom have theluxury of letting it “take hours oreven days for a new idea to sinkin”, as Lockhart advises. In themore relaxed and playful contextof Measurement, however, it seemsto work, and readers who try someof the easier puzzles will soonfind themselves ready for morechallenging fare. And if you do getstuck, Lockhart advises you to startworking on another problem, as “it’smuch better to have five or six wallsto bang your head against” thanonly one.●●2012 Harvard University Press£20.00/$29.95hb 416ppEinstein the inventorAlbert Einstein’s early career asa clerk in the Swiss Patent Officeis sometimes perceived as anaberration. Having failed to get ajob as a teacher, or to have his truetalents properly appreciated by thephysics establishment, the storygoes that he took this rather boringjob only because he needed to eat,or because it allowed him time toconstruct a gedankenexperiment ortwo in periods of idleness. There issome truth to this: although Einsteinlater looked back on the patentoffice with fondness (calling it “thatworldly cloister where I concoctedmy finest ideas”) he left his job thereas soon as he reasonably could,after obtaining an academic postat the University of Zurich. YetEinstein’s experiences of the patentoffice never really left him. Evenafter his theoretical work made himthe world’s most famous scientist,he maintained an avid interest intechnology and practical inventions.These inventions – along with hismusings and expert opinions onother people’s gadgets – are thesubject of The Practical Einstein:Experiments, Patents, Inventions byJózsef Illy, a visiting historian at theCalifornia Institute of Technology.In this slender book readers will findsome fascinating anecdotes aboutEinstein’s lesser-known scientificresults, including a refrigerator heinvented with Leó Szilárd and apaper he wrote on the meanderingsof rivers. Not all of these effortswere successful. For example,an experiment he conducted onmolecular currents in 1915 produceda result that, in Illy’s understatedwords, “did not stand the test oftime”. Similarly, Einstein’s careeras an impartial witness for patentdisputes – which began after hehad moved into academia – wasmarked by a number of lost casesand bungled court appearances.Even the successful and innovativeEinstein–Szilárd refrigerators werepreceded by Einstein’s abortiveefforts to develop an “ice machine”with his chemist colleague WaltherNernst. The Practical Einstein readsmore like a series of stories thana narrative, but Illy does deservecredit for gathering the oftenincomplete records of Einstein’spractical side into one book.●●2012 Johns Hopkins UniversityPress £31.50/$60.00hb 216pp64Physics World March 2013

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GraduateCareersMarch 2013Soft landingsThe skills you didn’t know you hadShutterstock/iuriiphysicsworld physicsworld.com brightrecruits.com

physicsworld.comGraduateCareersThe pleasure of finding things outThe ability to research a problemis one of many “soft skills” thatserve physics graduates wellin the job market, asNadya Anscombe describesMany students choose to do a physicsdegree because they like learning abouthow the world around us works. Fortunatelyfor those about to enter the job market asnew graduates, the natural curiosity that isa prerequisite for studying physics is alsoa prerequisite for many professions, eventhose that appear to have little connectionwith science. Finding information, siftingthrough it and extracting the importantbits are all skills that are needed in finance,market research, politics, police work andjournalism – to name just a few.It is widely accepted that physics graduatestend to be numerate, bright and wellinformed about some pretty esoteric subjects.In many workplaces, though, it is theircritical thinking skills that are in demand,says Peter Barham, a physicist and seniortutor at the University of Bristol who hasseen hundreds of students enter the jobmarket over the years. “Many jobs, suchas patent examiner or business consultant,require someone to collate a large amountof information and act on it,” he explains.“That’s basically what physics is all about”.Considering the sourceOne aspect of finding information is, ofcourse, having good formal research skills.During your degree, you were probablytaught how to carry out simple open-endedexperiments, use the library and mine variousdatabases for information. However,many of the research skills you will findmost useful in your future career are thoseyou picked up almost without realizing it.One of these, Barham suggests, is simplybeing able to find the right person to talk to.“When setting assignments, we try and setquestions that cannot be answered by doinga Google search,” he says. “We encouragestudents to knock on doors and ask for68advice. We also encourage them to talkto students in higher years as part of our‘parenting’ system”.Being able to glean information frompeople is a particularly important skill forjournalists. Valerie Jamieson, who is nowfeatures editor at New Scientist magazine,chose to study physics at the Universityof Glasgow because she felt it would giveher skills in many areas. Today, she usesresearch skills she learned during herundergraduate degree and her PhD tohelp her find out the “very human stories”behind scientific results.Another important – and related – skill,Jamieson says, is being able to analyse theinformation once she uncovers it. “In myjob, I see a lot of press releases, and sometimespress releases can overblow the significanceof results, which can go on to getreported,” she explains. “Understandingthe scientific method, how results get presentedand what uncertainties mean reallyhelps me to decide whether a story reallyis as significant as it is cracked up to be. Itmakes you better informed.”Research skills of this type are valued inthe commercial world, too. For example,companies looking to hire new employeesMany of the skills you will find most usefulyou picked up almost without realizing itmay look favourably on applicants withstrong research skills – even if researchas such is not part of the job description –because they tend to require less time andmoney to train, and will use their own initiativeto start providing new ideas quickly.Graduates who have good research skillsare also likely to be able to improve productsand services quickly. For example,project-based work may require researchskills to get a project off the ground.Know your strengthsIn the finance industry, skills such as analyticalthinking and problem solving arealways useful. When William Van De Pettegraduated from the University of Oxford,he knew he did not want to work in physics,but he wanted a job where he could applythe skills he had learned during his physicsdegree. Today he is a portfolio manager atinvestment management group HendersonGlobal Investors in London. “During mydegree I gained skills in research, analyticalthinking and problem solving, and theseare now skills I use every day in my job,”Van De Pette told Physics World. “I oftenhave to take maths problems and translatethem into real-world solutions. For this Iuse problem solving strategies I learnedduring my undergraduate years. I also frequentlyhave to find information by talkingto people, by e-mail and by reading reports,and then make investment decisions basedon what I find out.”A generalized “ability to find things out”Physics World March 2013iStockphoto/David H Lewis

physicsworld.comGraduateCareersis one of several so-called “soft skills” thatstudents pick up during a physics degreewithout understanding their importance toemployers, or even fully realizing that theyare acquiring them at all. Two other suchskills – giving presentations and acceptingcriticism – are explored later in this specialgraduate careers section, but this is far froman exhaustive list; team working, reportwriting, networking (see February pp44–45) and many others are also important.To establish what skills you have used,and how and when you have used them, thecareers manager of the Institute of Physics,Lindsey Farquharson, recommendsthat students undertake a “skills audit”.Using a resource produced by the Institute(“The physicist’s guide to getting themost from a physics degree”), studentscan establish what skills they have gainedfrom their degree and whether they haveevidence or examples to demonstrate theirmastery to potential employers. By the endof the exercise, she says, they should be ableto see which areas they need to work on,and which are well supported with numerousexamples. Being able to demonstratecompetence in these areas, she adds, couldbe the deciding factor between you andanother candidate with the same degree.Nadya Anscombe is a freelance writer based inBristol, UK, e-mail mail@nadya-anscombe.comDealing with criticismPhysics graduates areaccustomed to receivingfeedback from teachers, tutorsand lecturers, but differentexpectations and norms prevailin the workplace. Giles Morrisdiscusses how to handlecriticism at workiStockphoto/mediaphotosEntering full-time employment for the firsttime poses a steep learning curve, and eventhe best graduates are bound to make mistakesand encounter criticism. The trick isto respond positively when things go wrong,and turn things around when you get pulledup on errors.One thing that physics graduates, in particular,should be aware of is that the hard analyticalskills honed during a physics degreeare best left at the door when responding tocriticism. “Physicists should resist the temptationto over-analyse feedback,” says RussellColes, a human-resources consultantfor the energy firm EDF and former physicsteacher. “Taking an intellectually combativeapproach is best avoided. Emotional intelligenceand the ability to take a hint willprove more valuable.”It is also good to be aware of when andwhere you are likely to encounter criticism.Few managers nowadays will openlycriticize their staff in front of colleagues(although it still does sometimes happen),so you are most likely to come up againstcriticism in one-to-one meetings and annualappraisals. Other likely sources of criticisminclude e-mails and “track-changes” commentson reports or project documents.If you are called into a meeting room simplyto be told that you have done somethingwrong, you should treat the criticism as amatter of urgency. If criticism comes as partof a regularly scheduled meeting with yoursupervisor or line manager, it is probablya lower-grade issue, but it should still betaken seriously.Learning lessonsRegardless of the setting or their academicbackground, though, many graduatesare surprised to find that the criticismthey receive at work is far less direct ordetailed – and far more diplomatic – thanthe feedback they have grown accustomedto receiving in full-time education. Colessays that to some extent, this is just a partof British culture. “We don’t like confrontationand don’t like embarrassment,” hesays. “We tend to avoid the truth. We mightalso attempt to dilute the feedback.”Not all the differences are cultural, however.The bald truth is that new recruits areoften small cogs in a big machine, and managersmay not feel they have much investedin a new employee’s success or failures. It istherefore possible that they will not botherto go into painstaking detail, and willexpect employees to pick up on veiled clues.If a complaint has been made, managersmay want or need to preserve anonymity.As a consequence, new or relatively junioremployees may feel they have to acceptat face value whatever criticism is directedat them, says Simon Broomer, managingdirector of the career-planning firmCareerBalance. That, however, would be amistake, Coles argues, because employeesneed details in order to respond effectivelyto criticism. “Despite having just receivedsome bad news and although you are probablyangry and in denial, you really do needto appreciate the value of what you are beingtold,” he says. “Treat feedback as a gift.”In order to do this, Broomer suggeststhat employees should make a clear plan fordigesting criticism and turning the situationaround. First of all, he says, you shouldshow a positive attitude. “Try to avoid beingdefensive, criticising or blaming others,” hesays. “Stay positive, demonstrating that youtake the feedback seriously and are keen toimprove where you can.”Physics World March 2013 69

GraduateCareersphysicsworld.comCriticism should be treated as aspringboard for self-developmentOnce you have given the right impression,Broomer says, you can then dig fordetails by asking your manager to give specificexamples of occasions when you havenot done what they wanted, or behaved ina way they were not happy with. This canbe a way to find out if the criticism is basedon facts, or something less concrete. “Askyourself, ‘Is this an issue relating to my abilityto do the job, to my attitude or my behaviourtowards others?’,” Broomer suggests.If a negative remark was made by someoneelse, he adds, you can also ask for that personto be present to discuss the issue.Above all, Broomer thinks that criticismshould be treated as a springboard for selfdevelopment.“Ask for ongoing supportand coaching from your manager to helpyou improve,” he says. If the feedback youreceive indicates that you are missing skillsor knowledge, he explains, you can requestself-learning materials or off-site training ifyou believe that this will help you to acquirethem. Finally, he says, the employee andmanager should agree a specific time anddate – ideally no more than a month away –to review progress.The ability to take criticism on the chinand up your game in response to it may wellmark you out as somebody worth promoting.“The three most important attributesI looked for when recruiting were attitude,attitude and attitude,” says Coles.“Being resilient and bouncing back froma setback is powerful and can make quitean impression.”Dishing it outOnce you are on your way up the ladder ofpromotion, of course, the boot will be onthe other foot, and you will be called uponto give criticism to others. At that point, theexperience of receiving and acting on criticismwill hopefully help you to do it well.Constructive and appropriate feedback isan art in itself, and one that is often in shortsupply in today’s corporate environment.According to Coles, the key is to “be openand honest, but above all, constructive, andprovide accurate feedback and pinpointstrengths as well as weaknesses”.This advice is also valid when the personyou are criticizing is yourself. PeterWilford, career coach at Gateway CareerManagement, is adamant about the needfor regular self-assessment. “Ask yourself,‘How am I progressing? What do I needto do to reach the next level?’.” If you setpersonal and work goals and review themregularly, Wilford says, this type of selfcriticismwill help you take control of yourcareer. After all, he concludes, “It is up toyou and no-one else to drive it forward.”Giles Morris is a freelance writer based in London,e-mail giles@gilesmorris.co.ukMedal-winning presentationsSharon Ann Holgate examineshow lessons from sportspsychology can help physicsgraduates win over theiraudiences when it mattersiStockphoto/Goldmund LukicFrom announcing research results atconferences, to pitching for investmentand showcasing project plans to bosses orclients, most careers involve giving presentations.Presentations can also be integralto job interviews, may count towardsyour degree grade and are the backboneof many science outreach activities. Sowhether you enjoy the experience or itfills you with dread, it is crucial to learnhow to deliver the very best presentationsyou can in important, and often nervewracking,situations.Sportspeople, too, need to perform attheir best when it counts – no matter howthey are feeling, who they are competingagainst or what internal and external pressuresthey are facing. Indeed, an entirediscipline – sports psychology – has beendeveloped to help sportspeople deal withthese stresses, and workers in many professionshave adapted aspects of these techniquesto enhance their own performance.Might sports psychologists have somethingto offer to physics students, who need todeliver effective presentations both nowand in their future careers?The right way to practise“Practice” is one of the most commonpieces of advice given to people preparingpresentations. However, there is muchmore you can do to prepare than simplyrunning through the material over andover again.Richard Keegan, a sports psychologistat Australia’s University of Canberra, suggeststhat students should “build up, likean athlete would, from small manageablechallenges to full rehearsals”. He recommendsrehearsing a presentation first inprivate, then in front of friends or relatives,and finally asking a peer group to providea more critical audience. Try to keep anycriticism or mistakes – whether in rehearsalor the final presentation – in perspective,Keegan stresses. After all, he adds, errorsare “not going to result in your friends andfamily no longer loving you”.While practising, Keegan also suggeststhat students should think through worstcasescenarios and come up with a plan todeal with them. Kevin Sheridan, a postdocat the University of Sussex and oneof three UK physicists who agreed to tryout the tips presented in this article, found70Physics World March 2013

physicsworld.comGraduateCareersthat this advice helped him handle beinginterrupted with questions while deliveringa presentation to his research group.“Because I had mentally rehearsed thesesorts of situations, I was able to explainwhat I was trying to say without panic orfear,” says Sheridan.Sports psychologist Dave Smith, a seniorlecturer in exercise and sport scienceat Manchester Metropolitan University(MMU), recommends that students try tothink positively, both while practising andduring the actual presentation. “Sports psychologiststry to train golfers and snookerplayers to think positively after they messup a shot,” he explains. “If the player chastisesthemselves, they are likely to miss thenext shot, too.” If something goes wrongduring a presentation, he adds, it is importantto avoid panicking “because if you do,your chances of being able to sort the situationout become much less”.I think, therefore I canSmith also advocates building confidenceby imagining forthcoming presentationsusing an adapted form of the PETTLEPsystem (see box). This system was developedby some of his colleagues at MMUto provide sportspeople with a structuredway of using their imagination to motivatethem, improve performance, and increasetheir confidence. “There is a lot of evidencethat some of the same neural pathways inthe brain that are used when you do somethingare also activated when you imaginedoing it. So it can help prime you for thatactivity,” says Smith.Natalie Whitehead, a second-year physicsundergraduate at the University of Exeter,found that visualizing herself speakingin the venue helped her present her firstoutreach talk, which she gave to 15- and16-year-old pupils in a local school. “It givesyou a feeling for how it might turn out, soyou’re more prepared and more confident,”she says. When she worked in an engineeringconsultancy before her degree, Whiteheadadds, she would have found this andother advice in this article invaluable. “Youdidn’t have much guidance,” she explains.“You were just sent into client meetings andhad to present your results.”However, Pete Vukusic, a physicist atExeter who gave the Institute of Physics’Schools Lecture Tour in 2007, is moresceptical. Vukusic also played basketballat international level for the Englandunder-15, under-17 and under-19 squads,and while he agrees that visualization is“essential for sport”, in his view it is notnecessarily helpful for giving academicpresentations because the venue, audienceresponsiveness and equipment functionalityare often unknown.One way around this barrier is to visit avenue in advance or find pictures of it. Thatis part of the approach advocated by DaveCollins, who leads the Institute of Coachingand Performance at the University ofCentral Lancashire and is a former performancedirector of UK Athletics. Collinsadvises planning travel to the venue wellahead of time, and even trying out the journeyfrom hotel to venue if you are stayingnearby. He also recommends printing backupcopies of presentation slides on acetateoverheads and saving slides on a memorystick to allow for equipment failures.Combating nervesOn the day of the talk, Collins suggeststhat speakers try to distract themselves bydoing “something unrelated” an hour and ahalf before the presentation starts. Then, atleast 20 minutes before speaking, he recommendssetting up and checking your slides.When it is finally your turn to talk, he says,“think about the first few words or lines youare going to say. This should kick-start youinto your talk”. Accepting that you may getnervous can also help you deliver a goodpresentation. According to Collins, “thekey is to say ‘Okay, I’m put out by this, but it’sno worry because I know I’ve done everythingI possibly can to perform at my best’.”Charlotte Brand, a final-year student atExeter who regularly gives outreach talks,likes this approach. “It’s really helpful tohave someone say it’s okay to be nervous,”she says. “I think a lot of people find it veryhard to accept they are going to be nervous,and that makes them more nervousAccepting that you may get nervous canhelp you deliver a good presentationPETTLEP – Seven steps to imagining successful talksPhysical. Make your imagery multi-sensory, imagining how you will feel and move during yourpresentation, as well as thinking through the content.Environment. Make what you imagine, and where you do your imagining, as similar as possible to thepresentation location.Task. Rather than imagining something metaphorical such as pushing a rock up a hill, imagine thetasks required to give your presentation.Timing. Imagine delivering your presentation in real time to give an accurate sense of when you needto carry out each task.Learning. Continually update your imagery to accommodate anything you learn, concentrating in turnon different aspects of delivering your presentation.Emotion. Imagine the associated emotions positively so they worry you less. For example,vividly imagine being nervous, then imagine remaining calm and focused and giving a reallygood presentation.Perspective. To picture both perspectives, try imagining giving your talk and also being in theaudience watching yourself.and stressed.”But what if nerves do strike during yourpresentation? “A classic trick is to imaginethe anxiety is a liquid that can drain outfrom your body through taps in your fingersand toes. Or think about a calming,happy place like a beach,” advises Keegan.“If you find your heart is racing while youspeak, just pause for a moment and take adeep breath while you look at a slide or takea sip of water.”Another way to build confidence andeffectiveness, Keegan believes, is to makesure you get a good start by summarizingyour presentation in a couple of sentencesat the beginning. “Make it so clear youcould ‘sell it’ to someone you meet in anelevator,” he urges. The rest of the talk’sstructure is also important. Collins suggestsremoving any topics that are so complexyou will not have time to explain themproperly, and making sure the informationflows in a logical fashion.Ed Copeland, a University of Nottinghamphysicist who regularly gives outreach talksin schools and to the general public, agreesthat delivering “a take-home message” isimportant. Sheridan, however, found thatwhile this advice greatly improved an outreachtalk he gave for school pupils, it didnot work so well in a research presentation.“Colleagues want an argument built upblock by block with rigour,” he explains.However well you mentally and physicallyprepare, no presentation ever goesperfectly. So Collins emphasizes theimportance of making notes on what wentwell, and what aspects you can learn fromand work on for next time. And for anyonewho feels they are just no good at publicspeaking, Smith has one final piece ofadvice: persevere. “Practising in front ofsmaller audiences, and imagery, will helpyou improve your ability to give presentations,”he says.Sharon Ann Holgate (www.sharonannholgate.com)is a freelance science writer and broadcaster with aDPhil in physicsPhysics World March 2013 71

physicsworld.comGraduateRecruitmentwww.brightrecruits.comFind all the best graduate jobs, studentships and courses here in Physics World and online at brightrecruits.comSchool ofENGINEERING AND DESIGNBrunel rankedTop LondonUniversityestablishedin the last 50years (TimesHigherEducation)2012AwardwinningPlacementand CareersCentreBrunel isconvenientlylocated 20minutes fromLondonHeathrowAirport bycarwww.brunel.ac.ukPG taught courses are offered in:l Advanced Electronic and Electrical Engineering MScfull-timel Advanced Engineering Design MSc full-time andpart-timel Advanced Manufacturing Systems MSc full-time anddistance learningl Advanced Mechanical Engineering MSc full-timel Advanced Multimedia Design and 3D TechnologiesMSc full-time and part-timel Aerospace Engineering MSc full-timel Automotive and Motorsport Engineering MScfull-timel Biomedical Engineering MSc full-timel Building Services Engineering MSc full-time anddistance learningl Building Services Engineering Management MScdistance learningl Building Services Engineering with SustainableEnergy MSc full-time and distance learningl Computer Communication Networks MSc full-timel Design and Branding Strategy/Strategy andInnovation MA full-timel Embedded Systems MSc – MultimediaCommunications / Signal Processing full-timel Engineering Management MSc full-time and distancelearningl Integrated Product Design MSc full-timel Packaging Technology Management MSc full-time anddistance learningl Project and Infrastructure Management MSc full-timel Renewable Energy Systems MSc full-timel Sustainable Electrical Power MSc full-time andpart-timel Sustainable Energy: Technologies and ManagementMSc full-timel Water Enginerring MSc full-timel Wireless Communication Systems MSc full-timeSubject to approval:l Digital Design and Branding MSc full-timel Structural Integrity MSc full-timeFor further information andapplication form contact:PG courses: Marketing OfficeTelephone +44 (0)1895 265814Email sed-pg-admissions@brunel.ac.ukWeb www.brunel.ac.uk/sed/postgraduate-studyResearch: Research OfficeTelephone +44 (0)1895 266876Email sed-research@brunel.ac.ukWeb www.brunel.ac.uk/sed/researchFor information on student study experiences, view thespotlight newsletters at www.brunel.ac.uk/sedEPSRC Wind Energy SystemsDoctoral Training CentreWind EnergySystems ResearchStudentshipsStudy for a PhD with the UK’s leading University Wind EnergyResearch Centre and become qualified to contribute to thisdynamic and fast growing sector.The UK Wind Energy Research Centre at the University of Strathclyde ispleased to offer 10 prestigious 4 year EPSRC research studentshipsfor talented engineering or physical science graduates to undertake aPhD in wind energy research.Successful students will join the recently established EPSRC Centre forDoctoral Training in Wind Energy Systems, which is part of this nationalcentre of excellence at the University. Accreditation of the Wind CDTby the IET and IMechE enables students to develop professionallythroughout the course and gain all the competencies required forChartership.Course DetailsOur CDT offers a unique programme, combining training and researchwhich will aid graduates in transitioning into careers in the wind energysector. With proven and rapidly growing international demand for highlyqualified engineers and researchers, this course offers high leveltraining which is attractive to industries. To prepare for this excitingfuture, graduates will work closely with manufacturers, developersand researchers. This multidisciplinary programme brings togethergraduates from various science and technology disciplines to create aunique community of researchers. Training covers all aspects of windenergy systems including the wider socio-economic context.The PhD programme covers a number of disciplines that include:• Postgraduate-level training in all aspects of wind energy systems• Professional development enabled through course accreditation bythe IET and IMechE• Research and industrial engagementEntry RequirementsStudentships are available to UK and eligible EU citizens with (or aboutto obtain) a minimum of a 2.1 or a Masters degree in Physical Scienceor Engineering. These competitive Studentships will commence eachyear in October and will cover University fees and provide a highlycompetitive stipend.Applicants must be able to demonstrate enthusiasm, creativity,resourcefulness and a mature approach to learning.ApplyingTo apply now for October 2013 intake, please follow the applicationlink: https://ben.mis.strath.ac.uk/pguserprofile/control/enterDetailsPageFor further details on our Centre please visit:http://www.strath.ac.uk/windenergy/For further enquiries contact Drew Smith, CDT Administrator:Tel: 0141 548 2880Email: drew.smith@strath.ac.uk72Physics World March 2013

2013Teacher TrainingScholarShipSwww.iop.org/scholarshipsteach@iop.org0207 470 4959@physicsnewsTraiN To TEach • £20,000 ScholarShipS aVailaBlE • 100 To aWarD For 2013Do you wantto study for adoctorate whilstgaining invaluablecommercialexperience?Optics & Photonics TechnologiesL ED AD 0912 Scholar-4.indd 1 17/09/2012 11:05Industrial Doctorate CentreThe EngD is a 4-year fullyfunded PhD-level doctoratewith an emphasis on researchand development in acommercial environment.Successful candidates willnormally work closely withtheir chosen sponsoringcompany, with support froman Academic and IndustrialSupervisor. Funds are alsoavailable to support companyemployees who wish to studyfor an EngD whilst remainingin employment.FundingFees plus a stipend of at least£20,090 are provided foreligible students.Entry QualificationsMinimum entrancerequirement is a 2i Bachelorsor Masters degree in arelevant physical science orengineering topic.Further DetailsFor more details includinga list of current projects andeligibility criteria visitwww.engd.hw.ac.uk orcontactProfessor Derryck Reide: engd@hw.ac.ukt: 0131 451 3792Engineering Doctoratein Optics and PhotonicsTechnologieswww.engd.hw.ac.ukPhysics World March 201373

Graduate Scientific Software DeveloperBSc/MSc: £23,000-£26,000; PhD: £26,000-£29,000Tessella delivers software engineering and consulting servicesto leading scientific and engineering organisations across theglobe.We recruit high achievers from leading universities who arepassionate about combining their IT expertise with their scienceand engineering backgrounds to solve real-world problems.You will enjoy a varied and challenging role, working closelywith our clients to understand the business issues they face andhelping to design and develop innovative software solutions,being involved in all stages of the software developmentlifecycle. Projects can range from client based consultancy or ITdevelopment to office based client support activities.You should have:• BSc (min. 2:1), MSc or PhD in science, mathematicsor engineering• Programming experience in at least one of our corelanguages: Java, C#, C++, C, VB, .NET or PythonFor more details, visit:www.tessella.com/careershttp://www.bartlett.ucl.ac.uk/energyhttp://lolo.ac.ukTogether we’ll create your futureMSc in Biophysical SciencesFor 2013-14, UCL Energy Institute is offering the MRes inEnergy Demand Studies and brand new MSc inEconomics and Policy of Energy and theEnvironment.Work alongside experienced researchers in a dynamic,multidisciplinary environment and become one of the energypioneers of tomorrow.Applications welcome from candiates with a good firstdegree in a range of subjects (e.g. Economics, PhysicalSciences, Engineering, Mathematics). A background inenergy is not required.6 fully-funded four year (MRes + PhD)studentships in Energy Demand are also availableas part of the London-Loughborough Centre for doctoralresearch in energy demand. See website for eligilibity.The MSc in Biophysical Sciences has beencreated to bring excellent physical sciencegraduates to a position where they can start withconfidence in a wide range of careers in thebiophysical sciences. Created in response to thegrowing demand for graduates who can applytheir knowledge outside of the traditionalboundaries of their discipline, this courseprovides the essential tools and skills to excel inmultidisciplinary research.www.durham.ac.uk/bsi/postgraduatesClosing date 1st July 2013Image courtesy of Prof. R. Quinlan, Durham UniversityDeadline for funding: Monday 18th March74Physics World March 2013

FUSION DOCTOR AL TRAINING NET WORKPhD studentshipsFusion Energy: Materials and Plasma ScientistsThe Universities of Durham, Liverpool, Manchester, Oxford and York, with CulhamCentre for Fusion Energy, the Central Laser Facility and AWE have formed theFusion Doctoral Training Network: an EPSRC Centre for Doctoral Training.With ITER under construction and the operation of NIF in the US, fusion energy isentering an exciting new era. We work with world-leading facilities, including JET,MAST and the Central Laser Facility, while our Low Temperature Plasma researchis linked with major international companies in areas such as semiconductorprocessing.Our PhD programme offers:- fully funded 3 and 4-year research studentships- a training programme in fusion energy, covering materials and plasma science- exciting research projects, linked to world-leading fusion facilities- materials and plasma research projects for fusion energy- plasma projects in high energy density physics and laboratory astrophysics- opportunities for international collaboration and travelFor more information on the projects and application procedure visitwww.york.ac.uk/physics/fusion-dtnFuture-proofyour career.Study Photonics atthe OptoelectronicsResearch CentreAttend our open day to find out how studyingphotonics at the Optoelectronics ResearchCentre can lead to the brightest of futures.Uk students receive enhanced fundingincluding:–paid PhD tuition fees– tax free bursary up to £18kWe offer up to 10 scholarships for internationalMSc studentsOpen day 13 March 2013, 1.00-4.30pmBuilding 46, room 4050www.orc.southampton.ac.uk/visitus.htmlACRITASACRITAS (Actuation and Characterisation at the Single Bond Limit) isa Marie Curie Initial Training Network whose primary focus is advancedtraining and research in scanning probe-based nanoscience atthe single bond limit. ACRITAS runs for four years from Oct. 2012,involves eleven core partners and thirteen associate partners spanningacademia, industry, professional bodies, and NGOs.Research FieldsPhysics - Surface physicsChemistry - Physical chemistryEligibility criteriaCandidates must be in the first 4 years of their research careers andhave not been awarded a doctorate degree. Preference will be givento candidates with a first degree in Physics or Chemistry. (If the degreeis in Chemistry there should be a strong background in physicalchemistry). As part of our commitment to promoting diversity weencourage applications from women. All studentships are subject to theMarie Curie mobility and eligibility criteria described athttp://ec.europa.eu/research/mariecurieactions/ .The fellowship will entail secondments to at least one core and oneassociate network partner. See http://www.acritas.eu for a list of allACRITAS partners.VacanciesEight early stage researcher positions are nowavailable within the ACRITAS network and we invitesuitably qualified candidates to apply. Note thatall appointees will be expected to register for aPhD, must hold a primary degree of an appropriatestandard in a relevant subject (e.g. Physics,Chemistry, Materials Science – please contact thelead partner for the PhD project in which you’reinterested for advice), and must meet the MarieCurie mobility regulations.Funding organisation / ContactsUniversity of Nottingham Physics & AstronomyAcademicSchool of Physics and Astronomy,University of Nottingham,University Park,Nottingham NG7 2RD,United Kingdomhttp://www.nottingham.ac.uk/physics/research/nanoE-mails philip.moriarty@nottingham.ac.ukPhysics World March 201375

If you are graduatingthis year then your IOPmembership will lapseafter you graduate.Graduatingthis year?Don’t forgetto regradeyour IOPmembership!Choose from three options:• Associate Member – for early careerphysicists (including postgraduate students)wanting to maintain their professionalmembership.• IOPimember – this digital membership isperfect for anyone with an interest in physics.• Still an undergraduate? – if you arecontinuing your undergraduate studies pleaselet us know so we can extend yourfree membership.Regrading is easy!All you need to do is go to www.myiop.org, log inand then follow the instructions.Unless we hear from you by 30 September 2013your current student membership will expire inOctober 2013.Department of PhysicsThe University of York is the number 1 UK university in the world ranking ofuniversities under 50 years old.The Department of Physics is growing vigorously, with an investmentpackage during the last five years of 25 new academic posts, plus majornew laboratories and facilities including the York-JEOL Nanocentre, the YorkInstitute for Materials Research, the York Plasma Institute and Astrocampus.In addition to a dynamic and internationally renown research environment,we offer an active programme of post-graduate training including skills andprofessional development, and an attractive campus environment 2 kmfrom the centre of one of the most beautiful cities in the world.Postgraduate opportunitiesResearch in the Department of Physics at the University of York spans awide range of exciting fields in fundamental, cross-disciplinary and appliedphysics. Our internationally recognised research is organised into threegroups with strong ties to industry:• Condensed Matter Physics: nano and low-dimensional systems,magnetism and spintronics, quantum theory and applications &biophysics and organic systems• Nuclear Physics and Nuclear Astrophysics• Laser-Plasma Physics, Low Temperature Plasmas and Fusion energyWe offer PhD and MSc research degrees, as well as a 4-year PhD in theFusion Doctoral Training Network, a one-year taught MSc in Fusion Energyand a nine-month Graduate Diploma in Physics.PhD studentships are currently available with funding from the EPSRC/STFC, the Fusion DTN, industry sponsorship or The University of York. Somefunding is also available for the MSc in Fusion Energy.For more information visit www.york.ac.uk/physics/postgraduateor email the Graduate Admissions Tutor, Dr Yvette Hancock(y.hancock@york.ac.uk)THE UNIVERSITY OF BIRMINGHAMMSc in Physics and Technologyof Nuclear ReactorsContact: Dr Paul Norman,School of Physics & Astronomy, University of Birmingham,Edgbaston, Birmingham B15 2TTEmail: pin@np.ph.bham.ac.uk Phone: 0121 414 4660http://www.ph.bham.ac.uk/prospective/postgrad/pgptnr.html One year taught postgrad MSc. Next year starts 30/09/2013.Course structure refined over the 50 years the MSc has run.l Fully integrated labs and tutorials every week to bring togetherthe wide range of subjects and provide practical and writtenexamples and guidance in person.l Study courses on Reactor Systems, Reactor Physics andKinetics, Radiation Transport, Thermal Hydraulics, ReactorMaterials and more. PhD programs also possible.l Summer project, usually taken in industry and in many caseshas led to employment.l Sponsored by all the major players in the nuclear industry.PLACES/FUNDING CURRENTLY AVAILABLE76Physics World March 2013

CAREER VIDEOSThe application of physicists withina global engineering businessMissed the event in London on 28 November?No problem! The video recording is now available online atbrightrecruits.com/videos.Join us online, where Rolls-Royce demonstrates the main areas of thebusiness and the career and development opportunities that it offersphysicists, including:l “Submarines business overview” and “Civil nuclear business overview”with Steve LawlerPresented byVisit brightrecruits.com/videosTop Engineers EuropeOnline presentationsfrom April 2013Summit in Brussels26 - 27 April 2013Top Engineers GermanyOnline presentationsfrom May 2013Summit in Berlin6 - 7 May 2013An Ecolab CompanyAPPLY NOWAre you open to a great and unexpected career move?Top Engineers events connectsengineering graduates andprofessionals (in chemical, electrical, industrial, manufacturing,mechanical, software engineering,...) with leading global companieslooking to tackle tomorrow’s world challenges. Join us online throughexclusive presentations and/or at one of our summits in Brussels orBerlin for two days of interviews and workshops with internationalrecruiters. Help shape tomorrow’s business.By invitation only, so apply now.Free accommodation at the summits if you are invited.LIFE IS A JOURNEY. START YOURS ON WWW.CAREERSINTERNATIONAL.COMPhysics World March 2013CI ad for IOP 2013.indd 11/15/2013 12:06:03 PM77

Erasmus MundusMaster of Nanoscienceand Nanotechnology(EMM-nano)isityour next career moveCO-ORDINATOR: Katholieke Universiteit Leuven(Belgium)EDUCATIONAL PARTNERS:lKatholieke Universiteit Leuven (Belgium)lChalmers Tekniska Högskola, Göteborg (Sweden)lUniversité Joseph Fourier, Grenoble (France)lTechnische Universität Dresden (Germany)ASSOCIATED RESEARCH PARTNERS:lIMEC, Leuven, BelgiumlCEA-LETI, Grenoble, FrancelLeibniz Institute for Solid-State and Materials Research,Dresden, GermanyContact information:Prof. Guido Groeseneken (K.U.Leuven),Co-ordinator Erasmus Mundus Master of Nanoscienceand Nanotechnologynano@kuleuven.bewww.emm-nano.orgVisitr physics and engineeringGraduate coursework opportunitiesResearch School of Physics & Engineering (RSPE)RSPE is one of the world's premier centres for physics research.It is home to Australia’s world-class heavy-ion accelerator andplasma fusion research facility and a concentration of researchin photonics and non-linear optics. We offer a range of uniquegraduate coursework opportunities based on our researchstrengths:> Master of Energy Change> Master of Nuclear Science> Master of PhotonicsInformation & applications E pec@physics.anu.edu.auW physics.anu.edu.au/education/graduate_coursework.phpCRICOS #00120C | 140812PWThe jobs sitefor physics andengineering78site for physics and engineeringPhysics World March 2013

11 PhD &4 Post-DoctoralResearcherPositionsSpinIcurEC Funded project on Spin CurrentsA Marie Curie Initial Training NetworkThe network brings together 10 international partners and offers a totalof 11 Early Stage Research (ESR) PhD positions for 36 months and 4Experienced Researcher (ER) post-doctoral positions for 24 months.Spintronics offers the potential for logic operations that are fasterand consume much lower power when compared to conventionalsemiconductors. Passive spintronic devices are already the basis for amulti-billion dollar data-storage industry. The scientific goal of SpinIcur is tounderstand the fundamental physics of pure spin currents – where electricalcharge and spin are separate, their generation and propagation througheffects such as the spin Hall effect, spin pumping and the spin Seebeckeffect. The culmination of the research will be in exploring the fundamentalsof spin amplification in designs such as the spin-torque transistor for a newgeneration of spintronics devices.Positions available at• University of Leeds UK• INESC-MN Portugal• IBM Research Zurich Switzerland• International Iberian Nanotechnology Laboratory Portugal• University of Cambridge UK• Hitachi Cambridge Laboratory UK• University Regensburg Germany• Delft University of Technology Netherlands• Norwegian University of Science and Technology NorwayKey benefits• Generous salary and additional allowances to cover living costs andtravel, including a contribution to some family related expenses and thecost of annual travel back to home country.• Opportunities for international collaboration and travel to world classacademic and industrial partners.• Training in a range of state-of-the-art scientific skills, intellectual propertyand project management skills.• Secondment placements within the network’s industrial partners.• Funds to support their participation in the SpinIcur ITN European wideresearch and training events.How to applyShortlisting and interviews from April 2013 and posts available to commence soon after, so early applications are encouraged.Further information concerning the positions and projects, together with the full application procedure, is available at:www.spinicur.orgAre you a graduate, passionate about science, technology and engineering?At e2v we help search the cosmos for Earth-like planets, we treat the mostserious of illnesses and we keep millions of travellers safe as they flyaround the world…..and much, much more!Our graduates are given the opportunity to work onground-breaking projects like the Kepler space mission andthe Curiosity rover for Mars and follow a tailored developmentprogramme to give them the best start in their career.Successful candidates must hold, or be due to obtain in 2013,a minimum 2.2 classification in an engineering or science related degree.If you have the above qualifications, intellect and passion, please apply at www.e2v.comImage courtesyof NASA+44(0)1245 493493www.e2v.comPhysics World March 201379

Graduates!Plan your next move with brightrecruits.comLooking for employment?Find your perfect job on brightrecruits.com. With more than15 specialisms in physics and engineering to choose from,we have something for everyone.Interested in further studies?We have loads of international postgraduate opportunitiesjust waiting for your application.Need some advice?Our Careers insight section offers top tips on everything fromwriting a CV to succeeding in psychometric tests. Plus thereare some great case studies to help you to decide on yourfuture career.Register online with brightrecruits.com todaywww.brightrecruits.com/registerDon’t missout!GraduateCareersOctober 201380Physics World March 2013

physicsworld.comRecruitmentRecruitment AdvertisingPhysics WorldIOP PublishingTemple Circus, Temple WayBristol BS1 6HGTel +44 (0)117 930 1264Fax +44 (0)117 930 1178E-mail sales.physicsworld@iop.orgwww.brightrecruits.comThe place for physicists and engineers to find Jobs, Studentships, Courses, Calls for Proposals and AnnouncementsDEPARTMENT OF PHYSICSChair in ExperimentalTokamak PhysicsThe University of York is one of Britain’s leading universities, placed in thetop ten UK universities by the 2008 Research Assessment Exercise (RAE) andregularly ranks amongst the top 100 universities worldwide. The Universityand the Engineering and Physical Sciences Research Council have investedover £4m creating the York Plasma Institute in the Department of Physics,formally opened in October 2012 by Professor Sir John Beddington, the UKGovernment Chief Scientific Advisor.We are seeking an individual with an international reputation in ExperimentalTokamak Physics to join the research team at the York Plasma Institute. Youwill have an outstanding track record in plasma science, amongst the World’sleaders in the field. You will ideally have expertise in tokamak exhaustphysics, but very strong applicants with an internationally leading reputationin other areas of tokamak physics will also be considered. You will be expectedto provide research leadership and compete for research funding. Strongcollaboration with Culham Centre for Fusion Energy, including participationin the MAST and/or JET tokamak programmes is expected.Informal enquiries may be made to Prof Howard Wilson, Director of theYork Plasma Institute, email: howard.wilson@york.ac.ukFor further information and to apply on-line, please visit our website:http://www.york.ac.uk/jobs/Closing date: 13 March 2013.The University of York is committed to promoting equality and diversity.www.york.ac.ukPhysics World March 2013FACULTY POSITION INTHEORETICAL PHYSICSUNIVERSIDAD DE LOS ANDES –BOGOTA, COLOMBIAThe Physics Department at Universidad de los Andes, Colombia, is seeking to fill aposition in theoretical physics for a faculty member. We are looking for applicants witha strong theoretical background and with a wide range of research interests in theareas of Statistical Physics, Many-Body Physics, Quantum Field Theory, and QuantumInformation Theory.A Ph.D. degree and commitment to excellence in independent research and teachingis required. Postdoctoral experience is preferred. Interested applicants should send acurriculum vitae, a description of research and teaching interests, and arrange to havethree recommendation letters sent to:Carlos Ávila, e-mail: director-fisica@uniandes.edu.coChairman, Physics Department, Universidad de los AndesA.A. 4976, Bogotá, Colombia.Phone (57-1)-332-4500, Fax (57-1)-332-4516.First review date: March 30th, 2013. Position will remain open until filled.Position starting date: August 2013 or January 2014Visitfor your next career moveThe Diamond synchrotron light sourceis the largest scientific facility to be built inthe UK for over thirty years. The facility consistsof three particle accelerators which provide highbrightness photon beams to experimental stations.Diamond is now operational with an initial complementof 20 experimental stations and a further 12 in designand construction.If you are a capable software engineer this is an opportunity toparticipate in cutting edge research, developing software in anexciting scientific facility. The working environment is technicallydriven, full of motivated individuals applying software technologyto a wide range of technical problems.Software Engineerwww.diamond.ac.ukRef: DIA0808/SBSalary: CompetitiveIn this role, you will work closely with a team of scientists andengineers, to develop software to control the Diamond accelerators.This will involve software design, development and support of a suitea client side tools realised in C++, Python and Java. Candidates musthave a good honours degree in physics, mathematics or computerscience; experience of software engineering, and excellentprogramming skills in object orientated languages; and a goodunderstanding of mathematics and physics.Software Systems EngineerRef: DIA0800/SBSalary: CompetitiveIn this role, you will work closely with a team of scientists andengineers, to develop control systems on the Diamond photonbeamlines, and experiment stations. This will involve system design,software development and hands on commissioning of state of the artexperimental facilities. Candidates must have a good honours degreein physics, electronic engineering or computer science; experience ofsoftware engineering applied to real-time applications and excellentprogramming skills in C and or object orientated languages.Diamond is committed to equality of opportunities for all, and offera competitive salary (dependent upon skills, qualifications andexperience), comprehensive benefits, an index-linked pensionscheme and flexible working hours.For an application form and further information including workpermit and visa requirements for non-EU nationals please visit ourwebsite at www.diamond.ac.uk telephone our recruitment line on01235 778218 or write to us at the address below, quoting theappropriate reference number.For further information about this role please visit:www.diamond.ac.ukClosing date: 17th March 2013.Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus,Didcot, Oxfordshire OX11 0DE81

Postdoc and PhD Positions in Statistical Physics/Quantitative BiologyThe University of Cologne offers a Postdoc and a PhD position in theresearch groups of Prof. Michael Lässig and Prof. Johannes Berg within theframework of the Collaborative Research Centre SFB 680 “Molecular Basisof Evolutionary Innovations”.We are looking for highly motivated individuals who enjoy workingin an international team at the interface between statistical physics andquantitative biology. Current research topics include gene expression,molecular evolution, and genomics. Projects involve concepts and methodsfrom equilibrium and non-equilibrium physics and build on experimentalcollaborations. For more details, see www.thp.uni-koeln.de/~lassig/ andwww.thp.uni-koeln.de/~berg.Applicants should have a strong background in statistical physics and agenuine interest in biology. The appointment will start in autumn 2013 orearlier. Applications including a CV, publication list, research statement,and two letters of recommendation (one for the PhD position) mailedindependently should be sent to SFB 680, c/o Christa Stitz, Institute forTheoretical Physics, University of Cologne, Zülpicher Straße 77, D-50937Köln, Germany. Applications can also be sent by email in a single PDF-fileto cstitz@uni-koeln.de. Pre-application enquiries are welcome.Cologne University is an equal opportunity employer, the positions areopen to Eu and non-Eu members. For further information seehttp://www.sfb680.uni-koeln.de/openpositions.html.Chair/Reader inExperimental Neutrino PhysicsReference: A649 Professorial (minimum £59,669)/Reader £47,314 - £53,233Lecturer in Experimental NeutrinoPhysics Reference: A650 £32,267 - £36,298We wish to appoint two outstanding experimental particle physicists at the levelof Chair/Reader (equivalent to a Full Professor/Associate Professor respectively)and Lecturer (equivalent to an Assistant Professor) to lead/support an expansionof our experimental neutrino physics programme at current and future long baselinefacilities.You will be expected to develop a world-class research activity in this fi eld and willbe able to join an existing group working with the T2K collaboration at JPARC(one professor, one lecturer, two researchers and several PhD students) as wellas build up a Lancaster contribution to one of the future long baseline neutrinooscillation projects.Our department was ranked fi rst and equal-fi rst respectively in the 2008 and 2001UK Research Assessment Exercises (RAE) and is seeking to further enhance itsscientifi c standing.The posts are permanent and tenable from 1 October 2013. In addition to your researchactivities, you will also be involved with undergraduate and postgraduate teaching.Please contact Professor Peter Ratoff (Head of Department) if you wish to havean informal discussion about this opportunity: Email: p.ratoff@lancaster.ac.ukTel: +44 1524 593639.We are strongly committed to fostering diversity within our community as a sourceof excellence, cultural enrichment, and social strength. We welcome those whowould contribute to the further diversifi cation of our department.Closing date: 21 March.www.lancaster.ac.uk/jobsAt the Institute of Physics, we recognise theimportance of identifying and developing toptalent, and that graduates with practical workexperience present a much more attractiveproposition to your business.Through our ‘Top 40’ placements scheme, we areoffering to fund talented students on an eight-weeksummer placement with your organisation, so thatyou can connect with the cream of penultimate-yearundergraduate physics students.By taking part in this scheme you can bring newskills and a fresh perspective to your business,gain a skilled and motivated member of staff andultimately drive productivity.For more details about the IOP ‘Top 40’, please visitwww.iop.org/careers/top40placementsor contact Lindsey Farquharson atsummerplacements@iop.org82 Physics World March 2013

CERN Courier September 2012Thinking about the Future of Basic Science.EuropeanNew year.New start.New job?IBS/RISP has openings for:Accelerator Scientists/EngineersThe Institute for Basic Science (IBS) wasestablished by the Korean government in November2011 with the goal to create a world-class researchinstitute in the basic sciences. IBS/RISP is to developscientific and technical expertise and capabilities forthe construction of a rare isotope acceleratorcomplex (Rare Isotope Science Project, RISP) fornuclear physics, and medical and material scienceand applications.The IBS/RISP is seeking for qualified applicants towork for Rare Isotope Science Project (RISP) at itsheadquarters office in Daejeon, Republic of Korea.The positions are at the level of research fellow, andpostdoctoral research associates and acceleratorengineers. Persons with high-level researchachievement, extensive experience in large scaleaccelerator facility construction are given higherpriority. The starting date is as soon as possible.XFEL SEIZE THE CHANCEThe successful candidates will participate in the R&DEuropean and construction XFEL is a of is a accelerator multi-national systems non-profit for company RISP. that is currentlybuilding an X-ray free-electron laser facility that will open up new areas ofscientific If you have research. the appropriate When this facility skills is and completed are looking 2015, for its ultrashortX-ray a diverse flashes and interesting unique research employment opportunities opportunitywill attract scientists from allover the world to conduct ground-breaking experiments. We are a rapidlywe encourage you to apply. IBS/RISP is an equalgrowing team made of people from more than 20 countries. Join us now!opportunity employer; all applicants will be consideredon their merit. EXCITING Salary and benefits OPPORTUNITIESwill be decidedFind upon out negotiations more about our with exciting the Director opportunities of RISP for scientists, and will engineers andgraduate become students. effective Help upon develop signing X-ray the instrumentation contract. and other systems.Help create a research facility of superlatives that will provide X-rays ofunique quality for cutting-edge research physics, chemistry, the lifePlease send your application including CV andsciences and materials science.introduction toWORKING AT EUROPEAN XFELEnglish Ms. Y.H. is the LEE, working RISP language. Director’s We offer Office salary at and the benefits Institute similar to thoseof for public Basic service Science, organisations 70 Yuseong-daero in Germany, a free-of-charge 1689-gil company pensionscheme, Yusung-gu, generous Daejeon, relocation Korea, package and 305-811 support, international allowance fornon-German candidates hired from abroad, training opportunities etc.or e-mail to leeyh@ibs.re.kr.Applicants shouldJOINarrangeOURto haveNETWORKthree letters ofJoin references our network sent of to international address or research e-mail. institutions, programmes andcollaborations. Discuss problems and solutions with colleagues from all overthe Application world. deadline is August 31, 2012.Further information COME can be TO obtained HAMBURG by sending mailEconomically to leeyh@ibs.re.kr. and culturally, Hamburg is the centre of Northern Germany. Withits long history in trade, Hamburg has always been an outward-looking cityand Deadline one of Germany’s for applications: gateways 31 to the August world. 2012 Work and live in Hamburg, oneof the most beautiful and interesting cities in Europe!http://risp.ibs.re.krEuropean XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, GermanyMailing address: Notkestr. 85, 22607 Hamburg, Germanywww.xfel.euTry something new.extraordinaryJoBopportunitiesUnique opportunity to be involved in defining andimplementing the state-of-the-art laser technology andconstruction of a new EU science facility.wwwFrom software engineers to administrators, from fire fighters tohealth and safety officers – every kind of thinking is welcome here.Take your career somewhere special.www.eli-beams.eu/cooperation/jobs/Take partcern.ch/careerwwwPhysics World March 201383163769c (CERN) A5 Portrait.indd 1 07/11/2011 14:57

Lateral Thoughts: Gordon Fraserphysicsworld.comThe incomprehensibility principleEducators and psychologists invented the term “attentionspan” to describe the length of time anyone canconcentrate on a particular task before becoming distracted.It is a useful term but span, or duration, isonly one aspect of attention. Attention must also havean intensity – and the two variables are independentof each other. Perhaps one can postulate an analogueof the Heisenberg uncertainty principle, in which theintensity of attention multiplied by its span cannotexceed some fixed value. I call this the “incomprehensibilityprinciple” and I have had plenty of opportunitiesto observe its consequences.In the hands of skilled presenters, information canbe carefully packaged as entertainment so that theattention needed to digest it is minimal. The trick is tomask the effort with compelling emotional appeal anda floppy boy-band haircut. However, the need to payattention is still there; in fact, absorbing even the mosttrivial information demands a modicum of attention.How many of us, when leaving a cinema, have had thenagging feeling that although the film made for greatentertainment, some details of the plot remained lessthan crystal clear?The existence of a minimum level of attention suggeststhat it is, in some sense, a quantum substance. Thismeans that under close examination, any apparentlycontinuous or sustained effort at paying attention will berevealed as a series of discrete micro-efforts. However,while attention can be chopped up and interleaved withother activities, even tiny pulses of attention demandfull concentration, to the exclusion of all other voluntaryactivities. Any attempt at multitasking, such as using amobile phone while driving a car, is counterproductive.The incomprehensibility principle plays a major role ineducation, where it is closely linked to the learning process.Because of the subject matter and/or the teacher,some school lessons require more time to assimilatethan others. This trend accelerates in higher education.In my case, a hint of what was to come appeared duringmy third year of undergraduate physics, when I attendedadditional lectures on quantum mechanics in the mathematicsdepartment at Imperial College London.My teacher was Abdus Salam, who went on to sharethe Nobel Prize for Physics in 1979. Salam’s lectureswere exquisitely incomprehensible; as I look back, Irealize he was probably echoing his own experiences atCambridge some 15 years earlier at the hands of PaulDirac. He referred us to Dirac’s book The Principlesof Quantum Mechanics. At a first and even a secondglance this book shone no light at all, but after intensestudy, a rewarding glimmer of illumination appearedout of the darkness.Motivated by Salam’s unintelligibility, I began postgraduatestudies in physics only to find that my previousexposure to incomprehensibility had been merely anintroduction. By then, there were no longer any textbooksto fall back on and journal papers were impressively baffling.With time, though, I realized that – like Dirac’sbook – they could be painfully decrypted at “leisure”,line by line, with help from enlightened colleagues.The real problem with the incomprehensibility principlecame when I had to absorb information in real84The existenceof a minimumlevel ofattentionsuggeststhat it is, insome sense,a quantumsubstancetime, during seminars and talks. The most impenetrableof these talks always came from American speakersbecause they were, at the time, wielding the heavy cuttingtools at the face of physics research. Consequently,I developed an association between incomprehensibilityand accent. This reached a climax when I visitedthe US, where I always had the feeling that dubiouscharacters hanging out at bus stations and rest stopsmust somehow be experts in S-matrix theory and thelike, travelling from one seminar to the next. Severalyears later, when I was at CERN, seminars were insteaddelivered in thick European accents and concepts suchas “muon punch-through” became more of an obstaclewhen pointed out in a heavy German accent.Nevertheless, I persevered and slowly developed newskills. The incomprehensibility principle cannot bebypassed but even taking into account added difficultiessuch as the speaker’s accent or speed of delivery – not tomention bad acoustics or poor visual “aids” – it is stillpossible to optimize one’s absorption of information.One way of doing this is to monitor difficult presentationsin “background mode”, paying just enough attentionto follow the gist of the argument until a key pointis about to be reached. At that moment, a concertedeffort can be made to grab a vital piece of informationas it whistles past, before it disappears into the obscurityof the intellectual stratosphere. The trick is to dothis at just the right time, so that each concentratedeffort is not fruitless. “Only cross your bridges whenyou come to them,” as the old adage goes.By adopting this technique, I was able to cover frontiermeetings on subjects of which I was supremelyignorant, including microprocessors, cosmology andmedical imaging, among others. Journalists who findthemselves baffled at scientific press conferences woulddo well to follow my example, for the truth is that therewill always be a fresh supply of incomprehensibility inphysics. Don’t be disappointed!Gordon Fraser, a former editor of CERN Courier magazine, died inJanuary before this article could be revised. It was completed by staffat Physics World and is published both here and in CERN Courier thismonth as a tribute.Physics World March 2013iStockphoto/Francisco Romero

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