built, would be 100 times faster, largely
due to increased parallelism in measuring the error syndromes. Overall,
coordinated changes of physical technology, error correction mechanism,
and architecture may gain 3–4 orders
of magnitude in performance, demonstrating the impact of the field of quantum computer architecture.
A principal lesson learned so far in research on quantum computer architectures is that systems capable of solving classically intractable problems
will be large, although the search for
the smallest commercially attractive
machine continues. Device sizes will
limit integration levels, affecting architecture, and determining logical clock
speed requires making many design
decisions but dramatically affects what
can and cannot be effectively computed (as shown in Figure 1). Architectural
problems cover a broad range, but have
received only modest amounts of attention compared to near-term experimental hurdles, leaving much room
for high-impact research that can help
guide the focus of experimental work.
To sharpen the community focus on
building systems, it seems to be time
to begin demanding Moore’s Law-like
improvements in system capacity. Reviewers of papers and funding proposals should look for realistic estimates
of logical Toffoli gate time, incorporating error correction, for some target
logical fidelity. Even more ambitiously,
we recommend requiring realistic estimates of application performance.
Developing a sense of community is
critical. Creating a shared understanding including vocabulary, concepts, and
important problems among the physics
and CS theory, algorithm design, physics experiment, engineering, and architecture communities has proven to
be difficult, and few journals or conferences currently provide good venues for
such interdisciplinary endeavors, but
we expect the number will grow.
Let us close with a question that pro-
vokes answers ranging from, “Already
has,” (in reference to direct quantum
simulation of a specific quantum sys-
tem20) to “Twenty years,” to “Never,”—
and all these from people actually
working in the field:
When will the first paper appear in
Science or Nature in which the point is
the results of a quantum computation,
rather than the machine itself? That is,
when will a quantum computer do science, rather than be science?
This research is supported by the Cabinet Office, Government of Japan, and
the Japan Society for the Promotion
of Science (JSPS) through the Funding
Program for World-Leading Innovative R&D on Science and Technology
(FIRST Program). We thank Simon Devitt, Dave Farber, Joe Touch, Michio
Honda, Hajime Tazaki, Shigeya Suzuki, the referees and editors for careful
reading of the manuscript.
additional information and references for this article are
available under supplemental material in the aCm Digital
library DoI: 10.1145.249568.
1. bacon, D. and van Dam, W. recent progress in quantum
algorithms. Commun. ACM 53, 2 (Feb. 2010), 84–93.
2. beckman, D., Chari, a.n., Devabhaktuni, s. and Preskill,
J. efficient networks for quantum factoring. Phys.
Rev. A 54 (1996), 1034–1063; http://arXiv.org/quant-
3. brown, k.l., munro, W. J. and kendon, V.m. using
quantum computers for quantum simulation. Entropy
12, 11 (2010), 2268–2307.
4. buluta, I. and nori, F. Quantum simulators. Science
326, 5949 (2009), 108–111.
5. Childress, l. et al. Coherent dynamics of coupled
electron and nuclear spin qubits in diamond. Science
314, 5797 (2006), 281–285.
6. Clark, C.r., metodi, t.s., gasster, s.D. and brown, k.r.
resource requirements for fault tolerant quantum
simulation: the ground state of the transverse Ising
model. Phys. Rev. A 79, 6 (June 2009).
7. Devitt, s.J., Fowler, a.g., stephens, a.m., greentree,
a.D., hollenberg, l. C.l., munro, W. J. and nemoto, k.
architectural design for a topological cluster state
quantum computer. New Journal of Physics 11 (2009).
8. Devitt, s.J., Fowler, a.g., tilma, t., munro, W.J. and
nemoto, k. Classical processing requirements for a
topological quantum computing system. International
Journal of Quantum Information 8 (2010), 1–27.
9. Devitt, s.J., nemoto, k. and munro, W.J. Quantum
error correction for beginners. Reports on Progress in
Physics 76, 8 (aug. 2013).
10. DiVincenzo, D. the physical implementation of
quantum computation. Fortschritte der Physik 48, 9-11
11. Fowler, a., mariantoni, m., martinis, J. and Cleland,
a. a primer on surface codes: Developing a machine
language for a quantum computer. arxiv preprint
12. Fowler, a.g., Devitt, s.J. and hollenberg, l.C.
Implementation of shor’s algorithm on a linear
nearest neighbor qubit array. Quantum Information
and Computation 4, 4 (2004), 237.
13. gay, s. Quantum programming languages: survey and
bibliography. Bulletin of the European Association for
Theoretical Computer Science (June 2005).
14. Isailovic, n., Whitney, m., Patel, y. and kubiatowicz,
J. running a quantum circuit at the speed of data.
International Symposium on Computer Architecture.
Ieee (2008), 177–188.
15. Jiang, l., taylor, J.m., sørensen, a.s. and lukin, m.D.
Distributed quantum computation based on small
quantum registers. Phys. Rev. A 76 (Dec 2007).
16. Jones, n.C., Van meter, r., Fowler, a.g., mcmahon,
P.l., kim, J., ladd, t. D. and yamamoto, y. layered
architecture for quantum computing. Phys. Rev. 2,
(July 2012), 031007.
17. kielpinski, D., monroe, C. and Wineland, D.J.
architecture for a large-scale ion-trap quantum
computer. Nature 417 (2002), 709–711.
18. kim, J. and kim, C. Integrated optical approach
to trapped ion quantum computation. Quantum
Information and Computation 9, 2 (2009).
19. ladd, t., Jelezko, F., laflamme, r., nakamura, y.,
monroe, C. and o’brien, J. Quantum computers.
Nature 464 (mar. 2010), 45–53.
20. lanyon, b.P. universal digital quantum simulation with
trapped ions. Science 334, 6052 (2011), 57–61.
21. leibrandt, D. et al. Demonstration of a scalable,
multiplexed ion trap for quantum information
processing. Quantum Information and Computation 9,
22. levy, J.e. et al. Implications of electronics constraints
for solid-state quantum error correction and quantum
circuit failure probability. New Journal of Physics 13, 8
23. lloyd, s. a potentially realizable quantum computer.
Science 261 (1993), 1569–1571.
24. mariantoni, m. et al. Implementing the quantum von
neumann architecture with superconducting circuits.
Science 334, 6052 (2011), 61–65.
25. maslov, D., Falconer, s. and mosca, m. Quantum Circuit
Placement. IEEE Transactions on Computer-Aided
Design of Integrated Circuits and Systems 27, 4
26. metodi, t.s., thaker, D. D., Cross, a. W., Chong, F.t. and
Chuang, I.l. a quantum logic array microarchitecture:
scalable quantum data movement and computation.
In Proceedings of the 2005 International Symposium
on Microarchitecture (2005).
27. monz, t. et al. 14-qubit entanglement: Creation and
coherence. Phys. Rev. Lett 106, 13 (mar. 2011).
28. mosca, m. Quantum algorithms (2008); arxiv preprint
29. oi, D.k.l., Devitt, s.J. and hollenberg, l.C.l. scalable
error correction in distributed ion trap computers.
Physical Review A 74, 052313 (2006).
30. oskin, m., Chong, F.t., Chuang, I.l., and kubiatowicz,
J. building quantum wires: the long and short of
it. In Proceedings of the 30th Annual International
Symposium on Computer Architecture (June 2003),
31. raussendorf, r., harrington, J. and goyal, k.
topological fault-tolerance in cluster state quantum
computation. New Journal of Physics 9, 199 (2007).
32. schindler, P., barreiro, J.t., monz, t., nebendahl,
V., nigg, D., Chwalla, m., hennrich, m. and blatt, r.
experimental repetitive quantum error correction.
Science 332, 6033 (2011), 1059–1061.
33. shor, P. W. algorithms for quantum computation:
Discrete logarithms and factoring. In Proceedings
of the 35th Symposium on Foundations of Computer
Science. Ieee Computer society Press, los alamitos,
Ca, 1994, 124–134.
34. stace, t.m., barrett, s.D. and Doherty, a.C. thresholds
for topological codes in the presence of loss. Physical
Review Letters 102, 20 (2009).
35. svore, k.m., aho, a.V., Cross, a. W., Chuang, I. and
markov, I.l. a layered software architecture for
quantum computing design tools. IEEE Computer
(Jan 2006), 74–83.
36. Van meter, r., ladd, t. D., Fowler, a.g. and yamamoto,
y. Distributed quantum computation architecture
using semiconductor nanophotonics. International
Journal of Quantum Information 8 (2010), 295–323.
37. Van meter III, r.D. architecture of a Quantum
multicomputer optimized for shor’s Factoring
algorithm. Ph.D. thesis, keio university, 2006;
38. Vedral, V., barenco, a. and ekert, a. Quantum networks
for elementary arithmetic operations. Phys. Rev. A 54
(1996), 147–153; http://arXiv.org/quant-ph/9511018.
39. Wootters, W.k. and Zurek, W.h. a single quantum
cannot be cloned. Nature 299, 802 (oct. 1982).
40. yao, X.-C. et al. experimental demonstration of
topological error correction. Nature 482 (Feb. 2012),
Rodney Van Meter ( email@example.com) is an associate
professor in the Faculty of environment and Information
studies at keio university’s shonan Fujisawa Campus,
kanagawa Prefecture, Japan.
Clare horsman ( firstname.lastname@example.org) was a
project assistant professor at keio university’s sFC. she is
currently a research assistant at the university of oxford’s
Department of Cs, oxford, u.k.
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