ENTANGLEMENT OF GAUSSIAN STATES Gerardo Adesso

Foreword
Three years have passed quickly but at the same time filled with entertainment, work and new experiences
which have left an indelible footprint on my formation. I have shared this adventure with many
people, and it is a pity I cannot list them all here for brevity reasons.
Many thanks with sincere appreciation and esteem to my advisor Dr. Fabrizio Illuminati for all
the simultaneously funny and serious time, for having taught me how to make top-quality research
and how to write papers in a unique style. We had many animated discussions, and he was always
prompt to give me wise advices without ever imposing his point of view, or preventing me to take my
own decisions. Thanks also for his breathtaking attributes when referring to me in letters of support.
I am grateful to Prof. Silvio De Siena, who leads with Fabrizio the Quantum Theory and Quantum
Technologies Group in Salerno: his patience, experience and friendliness have been useful in several
critical moments. It is impossible not to smile while thinking of, and thanking my friend and colleague
Dr. Alessio Serafini (now at Imperial College, London), arguably the only person with whom I was able
to establish a ‘proper’ collaboration (and who managed to have me doing calculations with pencil and
paper): he is to be blamed for introducing me to continuous variable systems and Gaussian states. I
hope to keep sharing ideas with him, even though the shiny “basset-crew” trio (me, him and Fabrizio)
is now spatially separated.
During my PhD I had the luck of spending one year in the Centre for Quantum Computation
(CQC) of the University of Cambridge. I cannot recall how many interesting discussions (mostly at
lunch-time) arose there, and an estimate of how much the Cambridge experience was good for myself
(on both professional and personal grounds) would surely result in a lower bound. Hence I express all
my gratitude to my host Dr. Marie Ericsson for the joy of making physics together, for her enthusiastic
attitude towards work, and for the friendship born during my year at CQC. Accordingly, I thank Prof.
Artur Ekert, director of the CQC, who accepted me as a full member, and whose (quantum) capacity
of efficiently transmitting advices in short-time interactions is probably close to infinity.
I acknowledge collaborating with several researchers during these years. First, thanks to the
experimental group of Prof. Claude Fabre (Lab. Kastler-Brossel, Paris), and specifically to Dr. Julien
Laurat (now at Caltech), Dr. Thomas Coudreau, Gaëlle Keller and José Augusto Oliveira-Huguenin,
for the fruitful exchanges and for letting me see what a beam-splitter is in reality. Thanks also to
Tohya Hiroshima for welcoming our contribution to the proof of the monogamy of entanglement in
all Gaussian states, and to Ivette Fuentes-Schuller for the relativistic insights coming from our joint
project on continuous variable entanglement in non-inertial reference frames. I am furthermore deeply
grateful to a series of colleagues, not enumerated here, whom I met in various venues and with whom
I discussed for brief or long time, learning new things and understanding old ones.
Thanks to Alfonso and to all my friends, colleagues and officemates both in Salerno and in
Cambridge: time without them would have been duller and less productive. Thanks to my parents, my
sister and all close members of my family, for their neverending encouragement and for the trust they
placed in me. Special thanks to www.enigmi.net for keeping my brain active during this last year.
My unlimited thanks and love to Samanta, whom I had the pleasure and honor to marry in the
middle of our PhD. Thanks for all her support, hints, criticisms, proofreading, thanks for reminding me
of the sentence quoted in the caption of Fig. 5.1, thanks for all her delicious dinners, her sweetness,
her patience, her kisses, her love, for all her being herself. Thanks for making a better man out of
me... and for the miracle of life which blessed her and me.
v
Gerardo