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.

Conclusion

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?

Acknowledgments

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.

 

Supplemental Material additional information and references for this article are available under supplemental material in the aCm Digital library DoI: 10.1145.249568.

References

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- ph/9602016.

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

(2000), 771–783.

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 (2012); arXiv:1208.0928.

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, 3

(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, 901 (2009).

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 (2011).

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 (2008), 752–763.

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 arXiv:0808.0369.

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), aCm, n.y.

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;
arXiv:quant-ph/0607065.
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), 489–494.

 

Rodney Van Meter ( [e-mail]) is an associate professor in the Faculty of environment and Information studies at keio university’s shonan Fujisawa Campus, kanagawa Prefecture, Japan.

Clare horsman ( [e-mail]) 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.

Copyright held by owners/author(s)