Future Hardware Directions of Quantum Annealing 1cm Qubits Europe 2018 D-Wave Users

26 Pages·2017·7.23 MB·English

Future Hardware Directions of Quantum Annealing
Qubits Europe 2018
D-Wave Users Conference
Munich
Mark W Johnson
D-Wave Systems Inc.
April 11, 2018
Overview
Where are we today?
(cid:73)
(cid:73) annealingoptions
(cid:73) reverseannealing
(cid:73) quantummaterialssimulation
Where are we going?
(cid:73)
(cid:73) nextgenerationprocessor-improvedconnectivity
(cid:73) lowernoise
Copyright©D-WaveSystemsInc. 1/25
Overview
Where are we today?
(cid:73)
(cid:73) annealingoptions
(cid:73) reverseannealing
(cid:73) quantummaterialssimulation
Where are we going?
(cid:73)
(cid:73) nextgenerationprocessor-improvedconnectivity
(cid:73) lowernoise
Copyright©D-WaveSystemsInc. 2/25
The goal of quantum annealing (QA): model the Hamiltonian
(s) = 1 (s) ∑σ + (s)(cid:34) ∑hσ +∑J σ σ (cid:35) aΦ1X "spin-up" circulating current
S x,i i z,i ij z,i z,j
H −2 A B −
i i i<j
Φ 1
12 Φ2X "spin-down" circulating current
Φ 2
10 )
z Josephson
z) G H junction
GH 8 h( (cid:73) T. Kadowaki and H. Nishimori, PRE, 58(5), pp.
y ( 6 A/h( /B 5355-5363, (1998)
erg GH (cid:73) E. Farhi, et al., Science 292, 472 (2001)
En 4 z)
(cid:73) W. Kaminsky, S. Lloyd, T. Orlando,
2 arXiv:quant-ph/0403090, “Scalable
Superconducting Architecture for Adiabatic
0
0 0.2 0.4 0.6 0.8 1 Quantum Computation”
s
Copyright©D-WaveSystemsInc. 3/25
D-Wave 2000Q quantum annealing processor
Quantum processing unit = QPU
128,472 Josephson junctions
18,305 composite flux DACs
10,960 QFP shift register stages
4/25
2000 qubits: Chimera architecture at C16 scale
D-Wave Two D-Wave 2X 2000Q
Qubits (max) 512 1,152 2,048
Couplers 1472 3360 6016
Target Qubit Yield 95%+ 95%+ 97%+
Qubit degree Chimera, degree = 6
New features: Supporting more control over annealing:
(cid:73) Anneal Offsets
Give user per-qubit control over transverse field
(cid:73) Anneal Pause
Specify start and duration of global pause in anneal
(cid:73) Anneal Quench
Specify when to abruptly quench transverse field
(cid:73) Reverse Anneal: a new quantum algorithm
Copyright©D-WaveSystemsInc. 5/25
Standard annealing trajectory
(cid:34) (cid:35)
(s) ∑ (s) ∑ ∑
(s) = A σ + B hσ + J σ σ
S x,i i z,i ij z,i z,j
H − 2 2 −
i i i<j
12
10 )
z
H
z) G (cid:73) ratio A(s) a fixed function of s
(GH 8 A/ /h( for givBe(ns)qubit design
y 6 h( B
g
r G
e H (cid:73) trajectory: choose s(t) linear
En 4 z)
(cid:73) quadratic growth in B(s)
2
or ⇒
0
0 0.2 0.4 0.6 0.8 1
s
Copyright©D-WaveSystemsInc. 6/25
Modifications to the QA path: What is possible?
A(s) dashed, B(s) solid
12
10
8
Hz) (cid:73) Added control:
G
y ( 6 a per qubit offset
g
er
n
E 4 (cid:73) advance or delay individual
qubit schedule
2
0
0 0.2 0.4 0.6 0.8 1
s
Copyright©D-WaveSystemsInc. 7/25
Application: Factoring
Percentage of solved
instances
product standard delay long
size (bits) anneal chains
6 100% 100%
8 55% 100%
10 2% 98%
“Boostingintegerfactorizationperformanceviaquantumannealingoffsets”,E.Andriyash,etal.,2016
see“D-WaveWhitePapers”athttp://www.dwavesys.com/resources/publications
Copyright©D-WaveSystemsInc. 8/25
Modifications to the QA path: What is possible?
standard20µsannealingpattern
6 Manipulate global schedule:
Hz)4 pause mid-anneal
G
(
B(t)2
Why? What good does this do?
0
0 20 40 60 80 100 120 (cid:73) Useful for study of instances with
time(µs)
20µsannealwith100µspauseats=0.5 purturbative crossings
6
Hz)4 (cid:73) indentify regions during anneal where
G
( dynamics occur
B(t)2
0 (cid:73) probe of global freeze-out, localization
0 20 40 60 80 100 120 140
time(µs)
Copyright©D-WaveSystemsInc. 9/25