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Figure 5.3: Photolithography and Etching – a) Exposure: Irradiation with UV light changes the soluability of the photo-resist (PR). A mask is used to block the UV radiation where desired. Optics reduce the pattern by 5×. b) Development: Developer selectively removes the photo-resist. c) Completed development: The mask pattern has been replicated in the photo-resist. d) Etch: A mixture of ionized gases removes the metal where it is not protected by the photo-resist. e) Completed etch. f) Strip: A solvent removes the remaining photo-resist. g) Completion: The mask pattern has been replicated as traces on the wafer. photo-resist before it is placed into a machine called a “Stepper”. The Stepper exposes an array of 5× reduced copies of the base wiring pattern “printed” on the mask plate created in L-Edit. For this it shines UV light through a system of lenses and the mask onto the wafer for 1.2 s at a time. When all exposures are complete, the wafer is dipped into a developer like MF-701, which removes the more soluable parts of the photo-resist. This leaves a positive image of the mask pattern on the wafer as shown in Figures 5.3a-c. 94
5.3.3 ICP Etch Next, the wafer is loaded into a machine called an “ICP Etcher” (ICP = Inductively Coupled Plasma). Inside the etching chamber, the wafer is exposed to ions that will attack and remove the desired material. In this case, the chamber is filled with a low pressure mixture of BCl 3 and Cl 2 gas. An RF-plasma in the chamber dissociates the gas into BCl + 2 and Cl − ions. These are accelerated towards the wafer by an electrostatic bias. There, they contact the aluminum film wherever it is not protected by photo-resist. The Cl − ions will react with the aluminum to form aluminum chloride gas, which is pumped out of the chamber via a turbo pump. Since the etching is done primarily via the chemical reaction between the ions and the substrate and not via physical bombardment, this etching method can be highly selective in the materials that it will remove. For example, the above described chemical mixture will remove the deposited aluminum, but not the aluminum oxide (sapphire) wafer below it. 5.3.4 Photo-Resist Strip After the wafer comes out of the etching chamber, the remaining photo-resist is removed from it by a dip in acetone or in a chemical called “Stripper” which is specially formulated to effectively remove the given type of photo-resist. Some- 95
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UNIVERSITY of CALIFORNIA Santa Barb
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Benchmarking the Superconducting Jo
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viii
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Curriculum Vitæ Markus Ansmann Edu
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99:187006 Lisenfeld, J., Lukashenko
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Abstract Benchmarking the Supercond
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Contents Contents List of Figures L
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4.1.3 Readout Squid Parameters . .
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7.5.5 Grapher . . . . . . . . . . .
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11.5 Analysis and Verification . .
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List of Figures 2.1 Inductor-Capaci
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List of Tables 3.1 Transition Matri
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Chapter 1 Quantum Computation 1.1 M
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for such problems include factoring
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if present encrypted data will rema
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In terms of quantum bits, this mean
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1.2.3 Implications - The EPR Parado
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proposed architecture of quantum bi
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“coherence times”, i.e. the tim
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Chapter 2 Superconducting Josephson
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of the glue-circuitry needed to con
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Figure 2.1: Inductor-Capacitor Osci
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• The circuit needs to be cooled
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Figure 2.2: Josephson Tunnel Juncti
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the trace along the V-axis, gives c
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Figure 2.4: Josephson Qubits: Sligh
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the cosine forms a local minimum al
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Figure 2.5: Example Qubit Coupling
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Readout schemes can further be cate
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states in the qubit’s inductor, t
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at time t. r is not restricted to b
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3.1.2 Effects of a Time Dependent P
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In some cases, it is possible to so
Page 72 and 73: Figure 3.1: Examples of Numerical S
Page 74 and 75: • The energy difference between t
Page 76 and 77: like this: V = ( V (−1, −1), V
Page 78 and 79: Figure 3.2: Simulation of LC Oscill
Page 80 and 81: Table 3.1: Transition Matrix Elemen
Page 82 and 83: with ω mn = Em−En . Multiplying
Page 84 and 85: α, it can be ignored. Thus, the in
Page 86 and 87: e solved exactly: A(t + ∆t) = e
Page 88 and 89: qubits would be simulated using: A(
Page 90 and 91: This calculation assumes that the s
Page 92 and 93: Decoherence consists of two parts:
Page 94 and 95: Note the difference in signs of the
Page 97 and 98: Chapter 4 Designing the Phase Qubit
Page 99 and 100: mutual inductance between the qubit
Page 101 and 102: During the measurement, the | 1 〉
Page 103 and 104: the right impedance transformation
Page 105 and 106: excitations. Since these are a pote
Page 107 and 108: Figure 4.3: Squid I/V Traces - a) L
Page 109 and 110: Figure 4.5: Qubit Integrated Circui
Page 111 and 112: The geometry of the qubit junction
Page 113 and 114: squid loop. Thus, this tool can be
Page 115: now, amorphous silicon seems to pro
Page 118 and 119: Figure 5.1: L-Edit Mask Layout Tool
Page 120 and 121: Figure 5.2: Fabrication Building Bl
Page 124 and 125: times the removal can be a bit tric
Page 126 and 127: Figure 5.4: Clearing Vias from Nati
Page 128 and 129: 5.6 Junction Layers 5.6.1 Oxidation
Page 130 and 131: top wiring layer to protect all low
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Page 134 and 135: 6.1 Physical Quality Control during
Page 136 and 137: 6.1.3 Atomic Force Microscopy To re
Page 138 and 139: Figure 6.1: 4-Wire Measurement - a)
Page 140 and 141: 6.3 Quantum Measurements at 25 mK 6
Page 142 and 143: seems to be a box machined out of s
Page 144 and 145: Figure 6.2: Dilution Refrigerator W
Page 146 and 147: cessing data. This protects the vol
Page 148 and 149: 6.3.9 Anritsu Microwave Source The
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Page 152 and 153: ment, the scalability requirements,
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Page 156 and 157: 7.2.4 Performance Last, but certain
Page 158 and 159: or a Client Module. Client Modules
Page 160 and 161: second Module talks to all these an
Page 162 and 163: puters to talk to each other. Usual
Page 164 and 165: 7.3.4 Performance Addressing the Pe
Page 166 and 167: is designed such that the LabRAD Ma
Page 168 and 169: Table 7.3: LabRAD Type Annotations
Page 170 and 171: listed in Table 7.3. For transmissi
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Architecture to manage network conn
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Manager. In fact, in our lab, the o
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waiting for their completion. The C
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mentation of pipelining and certain
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Since the API guarantees that all R
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one microwave line for X/Y-rotation
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7.5.3 DC Rack Server The DC Rack Se
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data taking on the lab servers and
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keys and the ability to set Context
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a certain time. 7.5.9 Optimizer Cli
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ters read from different sub-direct
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efore the execution of the sequence
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can achieve very-close-to hardware
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type to provide a one-stop location
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172
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8.1 Squid I/V Response As explained
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a digital signal via the use of a c
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energy landscape (see Chapter 2.2.3
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Figure 8.3: Squid Steps Failure Mod
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At this point, the squid ramp can b
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starts to tunnel to the neighboring
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Figure 8.5: General Bias Sequence -
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Figure 8.7: Spectroscopy - a) Bias
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Figure 8.8: Rabi Oscillation - a) B
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ensemble with respect to each other
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Figure 8.10: T 1 - a) Bias sequence
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Figure 8.11: Ramsey - a) Bias seque
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phase shift into the middle of the
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photon excitation behaves similarly
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is desirable to modularize the cont
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sequence was run. This allows for t
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possible to read out all qubits cor
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simultaneous application of such me
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Figure 9.4: Capacitive Coupling Swa
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Figure 9.6: Capacitive Coupling Pha
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a phase difference of 0 ◦ rather
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Figure 9.7: Fine Spectroscopy of Re
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Figure 9.8: Swapping Photon into Re
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esonator. The latter calibration is
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Figure 9.11: Resonator T 1 - a) Seq
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224
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He does not throw dice” [Einstein
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(independent of which axis it is),
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of E xy is measured by expressing i
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For a measurement of two particles
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10.2.1 Photons The first and most n
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10.2.3 Ion and Photon In the attemp
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238
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11.1 State Preparation Since the ab
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Figure 11.1: Bell State Preparation
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Table 11.1: Entangled State Density
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Figure 11.2: Bell Measurements - a)
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11.2.3 Statistical Analysis For the
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11.3 Calibration The most difficult
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Table 11.4: Sequence Parameters - R
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ally determine an optimal value for
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ages are based on this method, incl
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equires to converge. Since the algo
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Table 11.7: Bell Violation Results
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Table 11.9: Error Budget - Capaciti
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Bell inequality. To make this claim
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11.5.2 Dependence of S on Sequence
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point where the measurement happens
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The second qubit is not driven and
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Figure 11.6: Resonator Coupled Samp
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From the resulting states, the 16 p
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Table 11.14: Error Budget - Resonat
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sponding to a violation by 244.0σ.
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educe energy decay and dephasing an
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John F. Clauser, Michael A. Horne,
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J. Majer, J. M. Chow, J. M. Gambett
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Matthias Steffen, M. Ansmann, Rados
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