William D. Oliver
Quantum Engineeringof Superconducting Qubits
EQuS @ RLE . Engineering Quantum Systems
Plasma Science and Fusion Center – IAP Seminar
Engineering Quantum Systems (EQuS) Group, MITQuantum Information and Integrated Nanosystems (QuIIN) Group, MIT-LL
10 January 2018
SNEQSE- 2WDO 11/04/17
Computing Development Timeline
2
Quantum computing is transitioning from scientific curiosity to technical reality
A new discipline – quantum engineering – is emerging to bridge this gap.2
Classical (Electronic) ComputingFirst vacuum tube
(1907)ENIAC
(1946)
First fully transistor-based computer: TX-0
(1953)
Transistor invented(1947)
4.5M transistors: Pentium(1998)
30k transistors: i8088(1971)
5B transistors: Xeon(2014)
Quantum Computing
Quantum computer proposed
(1981)
Shor’s algorithm & quantum error
correctionproposed(1994-95)
Milestones in Fundamental
Elements(2012-2016)
Quantum anneling& adiabatic QC
proposed(1998-2000)
SNEQSE- 3WDO 11/04/17
Superconducting qubits Quantum optics
Canada• Inst. for Quantum Computing (est. 2002)
– U. Waterloo and Perimeter Institute
China• Key Lab, Quantum Information, CAS (2001)• Key Lab, Solid-State Microstruct. (2004)• Q-comm on satellite
NV centersIon trap qubits Semiconducting qubits
Worldwide Investment(not an exhaustive list)
Singapore• Research Center on Quantum Information Science and Technology (est. 2007)
Australia• ARC Centers of Excellence
– Center for Quantum Computing Technology (est. 2000) – Engineered Quantum Systems (est. 2011)– $46M investment (banking / Government, 2015)
Japan• Gate-based QC
– RIKEN, universities, … • Coherent computing: ImPACT program
– Universities (Tokyo, Osaka, Kyoto, …)– Govt. labs (NICT, NII, NTT, RIKEN, …)– Industry (Mitsubishi, NEC, Toshiba, …)
Europe• Austria: Institute for Quantum Optics and Information (est. 2003)• Netherlands: QuTech (2014)…$50M investment from Intel• United Kingdom: National Quantum Technologies Program (2014)• EU: Quantum Flagship (2016)
United States• Joint Quantum Institute (est. 2007)
– Maryland / NIST / LPS (NSA)– Ions, neutral atoms, optical, superconductors
• Multi-agency government investments– Universities, DOE, DOC, DoD, NSA, industry …– Basic research and systems programs
IonQ
Q-Ctrl
Potential value of quantum computing for economic and information security is driving significant worldwide investment – currently estimated at $4 billion / year.
SNEQSE- 6WDO 11/04/17
Outline
• Introduction to quantum computing
• Superconducting qubits
• Quantum engineering– State of field
– Quantum control & filter engineering
– 3D integration
C. Macklin et al., Science (2015)
Dispersive Engineered TWPA 5x5 mm2 silicon chip
SNEQSE- 7WDO 11/04/17
How is a Quantum Computer Different?
Quantum computers rely on encoding information in a fundamentally different way than classical computers
Quantum ComputerClassical Computer“Bit” : classical bit
(transistor, spin in magnetic memory, …)“Qubit” : quantum bit
(any coherent two-level system)
• Superposition states• Probabilistic measurement:
Ex: If |𝜶| = |𝜷|, 50% | 𝟎 , 50% | 𝟏
• Discrete states• Deterministic measurement:
Ex: Set as 1, measure as 1
0 1
| 𝝍 = 𝜶𝟏𝟎
+ 𝜷𝟎𝟏
𝜶| 𝟎 + 𝜷| 𝟏
| 𝟏
Superposition:
Fundamental logic element
State
Measurement
“Or” | 𝟎
| 𝟎
| 𝝍
| 𝟏“And”
SNEQSE- 8WDO 11/04/17
How is a Quantum Computer Different?
Quantum computers rely on encoding information in a fundamentally different way than classical computers
Quantum ComputerClassical ComputerFundamental logic element
f(000)
f(001)
000
001
Computing
000
001
+ f(000)
f(001) +
𝜶′𝜶
𝜷 𝜷′
• N qubits: 2N components to one state
• Quantum parallelism & interference
• N bits: One N-bit state
• Change a bit: new calculation (classical parallelism)
000, 001, …, 111 (N = 3) 𝜶 𝟎𝟎𝟎 + 𝜷 𝟎𝟎 𝟏 + ⋯+ 𝜸|𝟏𝟏 𝟏 (N = 3)
+
+… …
“Bit” : classical bit(transistor, spin in magnetic memory, …)
“Qubit” : quantum bit(any coherent two-level system)
SNEQSE- 9WDO 11/04/17
Three Atoms…Eight Classical States
• For three qubits, eight possible states
4321
cccc
8765
cccc
This state requires eight complex numbers to specify it
87654321
,,,,,,, cccccccc
coupling coupling
atom 1 atom 2 atom 3
3-atom system(8 states)
c1
c2
c3
c4
c5
c6
c7
c8
SNEQSE- 10WDO 11/04/17
Quantum Parallelismcoupling coupling
atom 1 atom 2 atom 3
3-atom system
c1
c2
c3
c4
c5
c6
c7
c8
3-atom system
c1
c2
c3
c4
c5
c6
c7
c8
before pulse after pulse
Operates on entire system
simultaneously
State amplitudes are shuttled between
states
QuantumParallelism
EM pulse flips spin of atom 1(p-pulse)
SNEQSE- 11WDO 11/04/17
Quantum Interferencecoupling coupling
atom 1 atom 2 atom 3
3-atom system
+
3-atom system
c5
c6
c7
c8
c1
c2
c3
c4
before pulse after pulse
c5
c5
EM pulse puts spin of atom 3into superposition
(p/2-pulse)
| 𝟏
| 𝟎
+
SNEQSE- 12WDO 11/04/17
Quantum Interferencecoupling coupling
atom 1 atom 2 atom 3
_
3-atom system
c5
c6
c7
c8
c1
c2
c3
c4
before pulse after pulse
c5 + c6
c5 - c6
3-atom system
EM pulse puts spin of atom 3into superposition
(p/2-pulse)
| 𝟏
| 𝟎
+-
+
SNEQSE- 13WDO 11/04/17
Quantum Interferencecoupling coupling
atom 1 atom 2 atom 3
3-atom system
c5
c6
c7
c8
c1
c2
c3
c4
before pulse after pulse
c5 + c6
c5 - c6
3-atom system
EM pulse puts spin of atom 3into superposition
(p/2-pulse)
_
+
if c5=c6no amplitude
in state
QuantumInterference
SNEQSE- 14WDO 11/04/17
Quantum Interferencecoupling coupling
atom 1 atom 2 atom 3
3-atom system
c5
c6
c7
c8
c1
c2
c3
c4
before pulse after pulse
c5 + c6
c5 - c6
c7 + c8
c7 - c8
3-atom system
c1 + c2
c1 - c2
c3 + c4
c3 - c4Quantum
Parallelism
if c5=c6no amplitude
in state
QuantumInterference
EM pulse puts spin of atom 3into superposition
(p/2-pulse)
_
+
SNEQSE- 15WDO 11/04/17
0 1 X0 1
Gate-Based Approach:Single-Qubit Operation
X-gate: p-pulse around x-axis
Classical NOT-gate Quantum NOT-gate example: X-gate
Bloch Sphere Driving Field (envelope only)
0 1X-gate applied to qubit along +Z:
SNEQSE- 16WDO 11/04/17
0 1 X0 1
Gate-Based Approach:Single-Qubit Operation
X-gate: p-pulse around x-axis
Classical NOT-gate Quantum NOT-gate example: X-gate
Bloch Sphere Driving Field (envelope only)
0 1 0 1 X-gate applied to arbitrary qubit state:
SNEQSE- 17WDO 11/04/17
Gate-Based Approach:Two-Qubit Controlled-NOT
Rotation of QB-y depends on the state of QB-x
in yx0 1 0
For example:
out x y x y0 0 1 1
Results in an entangled state
(cannot be factored)
Universal gate-based quantum computation is achievable with a small set of single and two-qubit gates.
Quantum CNOT-gate
CNOT
in
out
QB-x
QB-y
“control” qubit
“target” qubit
“control” bit
“target” bit
Classical XOR-gate
0011
0101
0011
0110
SNEQSE- 18WDO 11/04/17
time
Computer
Algorithm
…000
Yin =
+
+
001
010
+ 011
Input state
Measurement
0 1
Output state
000
001
010
011
…
’ ~ 0
Algorithm encodes answer
into single output state
with high probability
’ ~ 1
g’ ~ 0
d’ ~ 0
Quantuminterference
Quantum Algorithm (Gate Model)
…
000
001
010
011
Quantum interference
g
d
000
001
010
011
…
Single-qubitoperations
Coupled-qubitoperations
SNEQSE- 19WDO 11/04/17
Intuitive Figure of Merit for Qubit Quality
Coherence time: The qubit’s lifetime
Gate time: Time required for a single operation
Time
State lost
Environmental disruptions
• Fast operations are desired; Classical processor: ~1 GHz (1 ns per op.)
Most lenient threshold for quantum error correction (to sustain computation): >103 operations per qubit lifetime
( * Rigorous metric: gate & readout fidelity > 99.5%, that is, < 0.5% error per operation)
State decayingQuantum state
One Figure of Merit * : (Coherence time) / (Gate time)
SNEQSE- 20WDO 11/04/17
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09
Series1
Qubit Modalities
Gate Speed (Hz)
Figu
re o
f Mer
it: C
oher
ence
Tim
e / G
ate
Tim
eNuclear Spin
in Silicon
Ensemble NMR
Optical Quantum Dot
Trapped Ion
Neutral Atoms
Viable qubit for scalingNot yet demonstrated to be viable
lowest thresholdfor quantum error correction
Electron Spin in Silicon
Solid State Quantum Dots
NV-Centers in Diamond
Superconducting Qubits
BestPerformanceTrapped-Ion Qubit
Gate time: 10-100 msCoherence time: 1-50 s
Gate time: 10 nsCoherence time: 100 ms
Superconducting Qubit
1 mm
|𝟎 = |𝟏 =| |
faster gates & RO
higherfidelity
SNEQSE- 21WDO 11/04/17
Quantum Computing Approaches
2048102451225612864
Bit-length of RSA Key
1 hour
1E-12
1E-06
1E+00
1E+06
1E+12
1E+18
age of theuniverse
4096
QuantumClassical
Proc
essi
ng T
ime
(h
ours
)
Key Annealing Applications:• Supply transport optimization• Sensor & satellite tasking• Pattern recognition (surveillance)
Shor’s Algorithm for Prime Factorization:RSA Key Decryption
Gate-Based Quantum Computer Quantum Annealing Computer
Key Gate-Based Applications:• RSA key decryption• Unsorted database searching• Quantum simulation
Travelling Salesman Problem:Route Optimization
Quantum speed-up exists over known classical algorithms
Unknown if quantum speed-up exists with this approach
SNEQSE- 22WDO 11/04/17
Outline
• Introduction to quantum computing
• Superconducting qubits
• Quantum engineering– State of field
– Quantum control & filter engineering
– 3D integration
C. Macklin et al., Science (2015)
Dispersive Engineered TWPA 5x5 mm2 silicon chip
SNEQSE- 23WDO 11/04/17
• Linear resonant circuit– Low loss: Q >> 1
How to Build an Artificial Atom
0
1
2 LC
p CL
Linear Resonant Circuit
SNEQSE- 24WDO 11/04/17
Normal
• Dissipationless (R=0 @ DC)
• Phase coherent
http://iqc.uwaterloo.ca/faculty-research/nanoelectronics-based-quantum-information-processing/files/useqip_sc_lupascu.pdf
Superconductivity
Superconducting
also NbN, TiN, NbTiN, …
http://hyperphysics.phy-astr.gsu.edu/hbase/tables/supcon.html
SNEQSE- 25WDO 11/04/17
• Linear resonant circuit– Low loss: Q >> 1– Low temperature: kT << h0
– Linear elements: harmonic
How to Build an Artificial Atom
0
1
2 LC
p CL
Linear Resonant Circuit
Energy Spectra of Quantum LC Circuit
Energy0
h
0h
0h
~1/Q
0
1
2
3
quantized electricalharmonic oscillator
(e.g., quantized EM field)
2 21 1ˆ ˆ ˆ2 2
H CV LI
V
I
ˆ ˆ, 0I V
Capacitiveenergy
Inductiveenergy
capacitor voltage (momentum p)
inductor current (position q)
current and voltage do not commute(cannot measure simultaneously with arbitrary precision uncertainty relation)
M.H. Devoret, Les Houches (1995)
SNEQSE- 26WDO 11/04/17
250 nm
Josephson Junctions (JJs)Nonlinear inductors
RL
SIS (Josephson) Junction~ 1 nm
sinc
II Current:
Voltage:dt
dV
p2
0
Ic is the critical current, which depends on superconductor material and insulator thickness0 = h/2e is the superconducting flux quantum and has value 2.07x10-15 Wb = 2.07 mA · pH = 2.07 mV · ps
SEM of Al shadow-evaporated Josephson junction
insulatorsuperconductor
superconductor~ 1
nm Inductance:J
dIV L
dt
SNEQSE- 27WDO 11/04/17
• Linear resonant circuit– Low loss: Q >> 1– Low temperature: kT << h0
– Linear elements: harmonic
How to Build an Artificial Atom
0
1
2 LC
p CL
Linear Resonant Circuit
Energy Spectra of Quantum LC Circuit
Energy0
h
0h
0h
~1/Q
0
2 cosJ
C
LIp
Josephson Junction: Nonlinear Inductor
sinC
I I 0
2
dV
dt
p
CLJ
• Nonlinear resonant circuit– Josephson tunnel junction– Anharmonic– Solid-state artificial atom
Energy Spectra of Quantum LC Circuit
Energy
CI VI ,,
Qubit
23h
12h
01h
0
1
2
3
0
1
2
3
SNEQSE- 28WDO 11/04/17
Device Testing in a Dilution RefrigeratorTemperature = 20 mK
11 resonator pkgs (5 res. / package)
Isolators / circulators
Mixing chamber plate (10 mK)
Microwave linesand attenuators
Microwave switches
3 qubit pkgs (2 qubits / pkg)
Filters and biasing lines
5 GHz has a thermal energy of 250 mK operate at 20 mK.Commercially available, turn-key dilution refrigerators.
SNEQSE- 29WDO 11/04/17
5 mm 0.5 mm 0.5 mm
Why Superconducting Qubits: Lithographic scalability
200-mm wafers(49 Reticles 16 chips)
-1
0
1
0
0.5
Magnetic Flux (/0)
Ener
gy
|0
|1
Qubit Design Determines Energy Levels of “Artificial Atom”• Manufactured/designed “atoms”
• Lithographic scalability (silicon)
Transmon capacitorand control lines
5-Transmon chip withreadout resonators
Tunable transmon qubit loop with junctions
Josephson junctions(aluminum)
5 mm
250 nm
SNEQSE- 30WDO 11/04/17
Why Superconducting Qubits: Nanosecond-scale gate operations
Dual-Channel, 2GS/s, 14-bit AWG Qubit Control via Microwave Pulses• Manufactured/designed “atoms”
• Lithographic scalability (silicon)
• RF and microwave control
• 100-MHz gate operations
SNEQSE- 31WDO 11/04/17
Why Superconducting Qubits: Remarkable improvements in qubit coherence
“Moore’s Law” for T2
Oliver & Welander, MRS Bulletin (2013)
Blue: MIT & LL
lowest thresholdsfor quantum error correction
several groups 100-150 us(Delft, IBM, MIT, Yale, …)
NIST/IBM, Yale, ...
MIT-LL Nb Trilayer
• Remarkable improvement in T1,2
– Materials– Fabrication– Design
• All major qubit types at MIT– Flux qubit: T2 = 23 us– 2D transmon: T2 = 100 us– 3D transmon: T2 = 150 us– C-shunt flux qubit: T2 = 100 us
• Planar resonators– TiN Q > 2 M– Al & Nb Q > 1 M
SNEQSE- 32WDO 11/04/17
Outline
• Introduction to quantum computing
• Superconducting qubits
• Quantum engineering– State of field
– Quantum control & filter engineering
– 3D integration
C. Macklin et al., Science (2015)
Dispersive Engineered TWPA 5x5 mm2 silicon chip
SNEQSE- 33WDO 11/04/17
Engineering Quantum Systems
Physics Materials &Fabrication
LogicalPrimitives
QuantumTestbeds
Predictions ofPerformance
• Hamiltonian simulations and design tools• New algorithms & error correction • Benchmarking, validation, verification• Simulation and design tools
• Integrated control electronics and optics• Control electronics, cryogenic CMOS, SFQ• Calibration and benchmarking• Optimal control & dynamical error suppression
2-10 QubitExperiments
• High-coherence materials, fabrication and 3D integration• Thermal, mechanical, electromagnetic management• Integrated electronics and optics• Advanced packaging and signal routing
• Fault-tolerant implementations• Quantum error correction• Logical controller, compiler, scheduler
FutureQuantumProcessor
Future quantum processor demonstrations will stand on physics, computer science, and engineering foundation
ComputerScience
Control &DSP
Analog & Digital Circuits
ComputerArchitecture
SNEQSE- 34WDO 11/04/17
Architectural Layers of a QIP
Layered ArchitectureSoftware: algorithm & interface
Hardware: physical qubitsN.C. Jones PRX 2, 031007 (2012)
SNEQSE- 35WDO 11/04/17
Layered ArchitectureCompiler & firmware:
Dedicated to achieving fault-tolerant
logical operations via error mitigation,
detection, and correction
N.C. Jones PRX 2, 031007 (2012)
logicaloperation
+error
correction
errordetection
+error
mitigation
physical qubits(faulty)
logical qubits(robust)
Architectural Layers of a QIP
SNEQSE- 36WDO 11/04/17
Layered Architecture
N.C. Jones PRX 2, 031007 (2012)
Architectural Layers of a QIP
Qubit Error DetectionUCSB / Google Group,
IBM & Delft demonstrations
J. Kelley et al., Nature 519, 66-69 (2015)
Also: A.D. Corcoles et al., & Riste et al., Nature Comm. (2015)
SNEQSE- 37WDO 11/04/17
Layered Architecture
Architectural Layers of a QIP
N.C. Jones PRX 2, 031007 (2012)
Capacitively shunted flux qubitT1 = 50 ms ; T2 = 100 ms
F. Yan et al., Nature Comm. 7, 12964 (2016)
SNEQSE- 39WDO 11/04/17
Layered ArchitectureEngineered Error Mitigation:
Dynamical Decoupling
Eg. Lacrosse Cradling
Architectural Layers of a QIP
N.C. Jones PRX 2, 031007 (2012)
SNEQSE- 40WDO 11/04/17
Quantum Control Demonstration:Reducing Decoherence During Free Evolution
Transverse Relaxation: T2* ~ 2.5 us
Linewidth: T2* = 1/(p FWHM) ~ 1.75 us
Rabi approximately T1- limited: TR ~ (4/3) T1
Echo approximately T1- limited: T2E ~ 2 T1
Gate fidelty (rand. benchmkg): F = 99.75%
Longitudinal Relaxation: T1 = 12 us
Nature Physics 7, 565 (2011)
SNEQSE- 41WDO 11/04/17
Free evolution of the phase
dephasing
Qubit Dephasing and Filter Function
SNEQSE- 42WDO 11/04/17
Free evolution of the phase
dephasing
Qubit Dephasing and Filter Function
010
exp ( ) exp ( )i
i t dtE t
SNEQSE- 43WDO 11/04/17
Free evolution of the phase
dephasing
for Gaussian-distributedfluctuations
Qubit Dephasing and Filter Function
Martinis et al., PRB 67, 094510 (2003), Ithier et al., PRB 72, 134519 (2005); Yoshihara et al., PRL 97, 167001 (2006), Cywinski et al. PRB 77, 174509 (2008)
010
exp ( ) exp ( )i
i t dtE t
22
01
2exp
2N
Ed S g t
SNEQSE- 44WDO 11/04/17
Free evolution of the phase
dephasing
sensitivity of qubit energy to fluctuations
for Gaussian-distributedfluctuations
Qubit Dephasing and Filter Function
Martinis et al., PRB 67, 094510 (2003), Ithier et al., PRB 72, 134519 (2005); Yoshihara et al., PRL 97, 167001 (2006), Cywinski et al. PRB 77, 174509 (2008)
010
exp ( ) exp ( )i
i t dtE t
22
01
2exp
2N
Ed S g t
SNEQSE- 45WDO 11/04/17
Free evolution of the phase
dephasing
sensitivity of qubit energy to fluctuations
strength (variance) of fluctuations
for Gaussian-distributedfluctuations
Qubit Dephasing and Filter Function
Martinis et al., PRB 67, 094510 (2003), Ithier et al., PRB 72, 134519 (2005); Yoshihara et al., PRL 97, 167001 (2006), Cywinski et al. PRB 77, 174509 (2008)
010
exp ( ) exp ( )i
i t dtE t
22
01
2exp
2N
Ed S g t
SNEQSE- 46WDO 11/04/17
Free evolution of the phase
dephasing
sensitivity of qubit energy to fluctuations Filter functionshapes noise
for Gaussian-distributedfluctuations
Qubit Dephasing and Filter Function
Engineered filter function depends on pulse sequence and windows the PSD S()
Martinis et al., PRB 67, 094510 (2003), Ithier et al., PRB 72, 134519 (2005); Yoshihara et al., PRL 97, 167001 (2006), Cywinski et al. PRB 77, 174509 (2008)
010
exp ( ) exp ( )i
i t dtE t
22
01
2exp
2N
Ed S g t
strength (variance) of fluctuations
SNEQSE- 47WDO 11/04/17
NO Dynam. Decoup.
Dynamical Decoupling: Noise Shaping Filters
(Ramsey, N=0)t
Xp/2 Xp/2
Frequency (MHz)
= 1 ms, p = 0 RamseySpin echo
S ~ 1/f
Filte
r Fun
ctio
n
0
1
0 54321
0.8
0.2
0.4
0.6
Nature Physics 7, 565 (2011); PRL 110, 040502 (2013)
SNEQSE- 48WDO 11/04/17
t
Xp/2 Xp/2
Frequency (MHz)
= 1 ms, p = 0 RamseySpin echo
S ~ 1/f
Filte
r Fun
ctio
n
NO Dynam. Decoup.(Ramsey, N=0)
WITH Dynam. Decoup.(spin echo, N=1)
t
Xp
Xp/2 Xp/2
/2 /2 0
1
0 54321
0.8
0.2
0.4
0.6
Dynamical Decoupling: Noise Shaping Filters with 1 p-pulse
Nature Physics 7, 565 (2011); PRL 110, 040502 (2013)
SNEQSE- 49WDO 11/04/17
Frequency (MHz)
= 1 ms, p = 0 RamseySpin echo
S ~ 1/f
Filte
r Fun
ctio
n g(
t)
0.8
0.2
0.4
0.6
0
1
0 54321
NO Dynam. Decoup.(Ramsey, N=0)
WITH Dynam. Decoup.(CPMG, N=2)
t
Xp/2 Xp/2
t
Xp
Xp/2 Xp/2
/4 /2
Xp
/4
Dynamical Decoupling: Noise Shaping Filters with 2 p-pulses
Nature Physics 7, 565 (2011); PRL 110, 040502 (2013)
SNEQSE- 50WDO 11/04/17
Layered Architecture
Architectural Layers of a QIP
N.C. Jones PRX 2, 031007 (2012)
Engineered Error Mitigation:Dynamical Decoupling
(improves the physical qubit error rate)
J. Bylander et al., Nature Phys. 7, 565 (2011)
SNEQSE- 51WDO 11/04/17
Outline
• Introduction to quantum computing
• Superconducting qubits
• Quantum engineering– State of field
– Quantum control & filter engineering
– 3D integration
C. Macklin et al., Science (2015)
Dispersive Engineered TWPA 5x5 mm2 silicon chip
SNEQSE- 52WDO 11/04/17
Frequency-Tunable Transmons
Single Qubit Gates Coupled Qubit Gates
M. Kjaergaard, P. Krantz, T. W. Larsen, M. Kimchi-Schwarz, D. Rosenberg, J. Yoder, D. Kim, S. Gustavsson & W. D. Oliver
SWAP
5-Transmon Chip
C-phase
High coherence times, but single-layer process.Routing I/O to 2D array is challenging.
SNEQSE- 53WDO 11/04/17
Quantum-to-Classical Interface Today(few-qubit experiments)
Superconducting qubits in a dilution refrigerator
Quantum-to-Classical Interface as it looks today…
Trapped ionson an optical table
Need an extensible approach to realize practical quantum information processors
Superconducting Qubits Trapped Ion Qubits
SNEQSE- 54WDO 11/04/17
3D Integration for Quantum ProcessorsIARPA Quantum Enhanced Optimization
SiliconMCM
Coplanar WaveguideTransition to MCM
Ribbon Bonds
RF Wiring Harness
QubitChip
Printed CircuitBoard
Metal Carrier
Microbumps
dc Wiring Harness
Wire Bonds
Interposer
Readout/interconnect
Qubitchip
Parametric readout amplifiersand qubit bias/control routing
Qubit 1
~100 mm
High-Q metal
Thick ground plane
Qubit 2
Qubitbias
Fewmm
Large, isolated qubit mode
volume Coupling
Through-silicon vias
In bumps
3-Stack enables high connectivity while maintaining high qubit coherence
SNEQSE- 55WDO 11/04/17
3D Integration for Quantum ProcessorsIARPA Quantum Enhanced Optimization
SiliconMCM
Coplanar WaveguideTransition to MCM
Ribbon Bonds
RF Wiring Harness
QubitChip
Printed CircuitBoard
Metal Carrier
Microbumps
dc Wiring Harness
Wire Bonds
Interposer
Readout/interconnect
Qubitchip
Parametric readout amplifiersand qubit bias/control routing
Qubit 1
~100 mm
High-Q metal
Thick ground plane
Qubit 2
Qubitbias
Fewmm
Large, isolated qubit mode
volume Coupling
Through-silicon vias
In bumps
Coupled superconducting qubitsFlux qubits for quantum annealing
50-100 us coherence times: Z1-10 us coherence times: X & Z
Circuit-model QC50-100 us coherence times
Yan et al., Nature Comm. (2016)MIT / MIT-LL (2017)
Kelly et al., Nature (2015)
Qubit layer fabrication used for both gate-model and QA qubits (they are different!)
SNEQSE- 56WDO 11/04/17
3D Integration for Quantum ProcessorsIARPA Quantum Enhanced Optimization
SiliconMCM
Coplanar WaveguideTransition to MCM
Ribbon Bonds
RF Wiring Harness
QubitChip
Printed CircuitBoard
Metal Carrier
Microbumps
dc Wiring Harness
Wire Bonds
Interposer
Readout/interconnect
Qubitchip
Parametric readout amplifiersand qubit bias/control routing
Qubit 1
~100 mm
High-Q metal
Thick ground plane
Qubit 2
Qubitbias
Fewmm
Large, isolated qubit mode
volume Coupling
Through-silicon vias
In bumps
Readout/interconnect layer routes wires and amplifies signals8-layer planar Niobium process for efficient wire routing
M6
M5
JJ5
M7
Josephson JunctionTraveling Wave Parametric Amplifier
Macklin et al., Science 350, 307 (2015) Tolpygo et al., IEEE Trans. (2014)
SNEQSE- 57WDO 11/04/17
SiliconMCM
Coplanar WaveguideTransition to MCM
Ribbon Bonds
RF Wiring Harness
QubitChip
Printed CircuitBoard
Metal Carrier
Microbumps
dc Wiring Harness
Wire Bonds
Interposer
Readout/interconnect
Qubitchip
Parametric readout amplifiersand qubit bias/control routing
Qubit 1
~100 mm
High-Q metal
Thick ground plane
Qubit 2
Qubitbias
Fewmm
Large, isolated qubit mode
volume Coupling
Through-silicon vias
In bumps
Interposer isolates qubit from readout/interconnect layer.Superconducting through-silicon vias provide connectivity.
210 mm
Patterned TiN
Through-silicon via lined with TiN
3D Integration for Quantum ProcessorsIARPA Quantum Enhanced Optimization
Donna Yost, Justin Malek et al., (2017)
SNEQSE- 58WDO 11/04/17
SiliconMCM
Coplanar WaveguideTransition to MCM
Ribbon Bonds
RF Wiring Harness
QubitChip
Printed CircuitBoard
Metal Carrier
Microbumps
dc Wiring Harness
Wire Bonds
Interposer
Readout/interconnect
Qubitchip
Parametric readout amplifiersand qubit bias/control routing
Qubit 1
~100 mm
High-Q metal
Thick ground plane
Qubit 2
Qubitbias
Fewmm
Large, isolated qubit mode
volume Coupling
Through-silicon vias
In bumps
Tilt < 0.25 mrad
Fabricated In bumpsCross-section of
bump-bonded chips
3D image of bump-bonded chips
IR image of bump-bonded chips
Alignment ~1 µm
Indium bumps connect chips and provide electromechanical joining
3D Integration for Quantum ProcessorsIARPA Quantum Enhanced Optimization
Danna Rosenberg et al., npj Quantum Information (2017)
SNEQSE- 59WDO 11/04/17
Packaged qubit with flip chip bonded on top
6 identical qubits coupled to quarter wave resonators
0 10 20 30 40 50
20
40
60
80
100
T1~19 ms
0 10 20 20 40 50
100
80
60
40
20
Sign
al [m
V]
Time (ms)
Coherence Times(T1, T2 ~ 15-25 ms)
D. Rosenberg, D. Yost, R. Das, L. Racz, et al. (2015)
Over past 12 months, have demonstrated four critical building blocksElectrical
conduction
Interposer
Qubit chip
Proximal surface
Qubit chip
Si chip
Inductive coupling
Interposer
Qubit chip
Capacitive coupling
Interposer
Qubit chip
Coherence times comparable to planar qubits of same design
3D IntegrationFlip-Chip Bonding
SNEQSE- 60WDO 11/04/17
equs.mit.edu
SNEQSE- 61WDO 11/04/17
Team and collaborators
MIT EQuS Group
sponsorship
NEC/RIKEN/Tokyo Fumiki Yoshihara (NICT)Yasunobu Nakamura
MIT Lincoln Laboratory
UC BerkeleyJohn ClarkeIrfan Siddiqi
Peter BaldoJeff BirenbaumVlad BolkhovskyGreg CalusineJohn ChiaveriniEric Dauler (GL)Rabi DasGeorge Fitch Mark Gouker (ADH)Gerry HollandDavid HoverJamie Kerman (co-PI)David KimJustin MallekKaren MagoonLee MaillhotAlex MelvilleJovi MiloxiPeter Murphy
Kevin ObenlandWilliam D. Oliver (co-PI)Brenda OsadchyJason PlantJeanne PorterLivia Racz (AGL)Danna RosenbergJeremy SageGabriel SamachAdam Sears
Rick SlatterySergey TolpygoSteve WeberTerry WeirWayne WoodsAlex WynnJonilyn YoderDonna YostScott Zarr
Amy GreeneBharath KannanUwe Luepke Tim MenkeJack QiuYoungkyu Sung
EQuS
Daniel CampbellMorten KjaergaardPhilip KrantzJoel WangFei Yan
Mirabella Pulido
Simon GustavssonTerry OrlandoWilliam D. Oliver
ChalmersJonas Bylander
JuelichGianluigi Catelani
Brian MillsFancisca VasconcelosMegan Yamoah
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