Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Quantum computing in molecular magnets

Abstract

Shor and Grover demonstrated that a quantum computer can outperform any classical computer in factoring numbers1 and in searching a database2 by exploiting the parallelism of quantum mechanics. Whereas Shor's algorithm requires both superposition and entanglement of a many-particle system3, the superposition of single-particle quantum states is sufficient for Grover's algorithm4. Recently, the latter has been successfully implemented5 using Rydberg atoms. Here we propose an implementation of Grover's algorithm that uses molecular magnets6,7,8,9,10, which are solid-state systems with a large spin; their spin eigenstates make them natural candidates for single-particle systems. We show theoretically that molecular magnets can be used to build dense and efficient memory devices based on the Grover algorithm. In particular, one single crystal can serve as a storage unit of a dynamic random access memory device. Fast electron spin resonance pulses can be used to decode and read out stored numbers of up to 105, with access times as short as 10-10 seconds. We show that our proposal should be feasible using the molecular magnets Fe8 and Mn12.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Double well potential seen by the spin due to magnetic anisotropies in Mn12.
Figure 2: Feynman diagrams F that contribute to S(5)m,s for s = 10 and m0 = 5 describing transitions (of 5th order in V) in the left well of the spin system (see Fig. 1).

References

  1. Shor, P. in Proc. 35th Ann. Symp. Foundations of Computer Science (ed. Goldwasser, S.) 124–134 (IEEE Computer Society Press, Los Alamitos, 1994).

    Book  Google Scholar 

  2. Grover, L. K. Quantum computers can search arbitrarily large databases by a single query. Phys. Rev. Lett. 79, 4709–4712 (1997).

    Article  ADS  CAS  Google Scholar 

  3. Lloyd, S. Quantum search without entanglement. Phys. Rev. A 61, R010301-1–010301-4 (1999).

    Article  MathSciNet  Google Scholar 

  4. Ekert, A. K. & Jozsa, R. Quantum computation and Shor's factoring algorithm. Rev. Mod. Phys. 68, 733–753 (1996).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  5. Ahn, J., Weinacht, T. C. & Bucksbaum, P. H. Information storage and retrieval through quantum phase. Science 287, 463–465 (2000).

    Article  ADS  CAS  Google Scholar 

  6. Thiaville, A. & Miltat, J. Magnetism: small is beautiful. Science 284, 1939–1940 (1999).

    Article  CAS  Google Scholar 

  7. Thomas, L. et al. Macroscopic quantum tunnelling of magnetization in a single crystal of nanomagnets. Nature 383, 145–147 (1996).

    Article  ADS  CAS  Google Scholar 

  8. Friedman, J. R., Sarachik, M. P., Tejada, J. & Ziolo, R. Macroscopic measurement of resonant magnetization tunneling in high-spin molecules. Phys. Rev. Lett. 76, 3830–3833 (1996).

    Article  ADS  CAS  Google Scholar 

  9. Sangregorio, C., Ohm, T., Paulsen, C., Sessoli, R. & Gatteschi, D. Quantum tunneling of the magnetization in an iron cluster nanomagnet. Phys. Rev. Lett. 78, 4645–4648 (1997).

    Article  ADS  CAS  Google Scholar 

  10. Wernsdorfer, W., Sessoli, R., Caneschi, A., Gatteschi, D. & Cornia, A. Nonadiabatic Landau-Zener tunneling in Fe8 molecular nanomagnets. Europhys. Lett. 50, 552–558 (2000).

    Article  ADS  CAS  Google Scholar 

  11. Fitzgerald, R. Pulse shaping improves efficiency of soft X-ray harmonic generation. Phys. Today 53, 24–28 (2000).

    Article  Google Scholar 

  12. Cohen-Tannoudji, C., Diu, B. & Laloë, F. Quantum Mechanics Vol. 2, 1323–1339 (Wiley, New York).

  13. Barra, A. L., Gatteschi, D. & Sessoli, R. High-frequency EPR spectra of a molecular nanomagnet: Understanding quantum tunneling of the magnetization. Phys. Rev. B 56, 8192–8198 (1997).

    Article  ADS  CAS  Google Scholar 

  14. Mirebeau, I. et al. Low-energy magnetic excitations of the Mn12-acetate spin cluster observed by neutron scattering. Phys. Rev. Lett. 83, 628–631 (1999).

    Article  ADS  CAS  Google Scholar 

  15. Leuenberger, M. N. & Loss, D. Spin tunneling and phonon-assisted relaxation in Mn12-acetate. Phys. Rev. B 61, 1286–1302 (2000).

    Article  ADS  CAS  Google Scholar 

  16. Leuenberger, M. N. & Loss, D. Incoherent Zener tunneling and its application to molecular magnets. Phys. Rev. B 61, 12200–12203 (2000).

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We thank G. Salis and J. Schliemann for useful comments. This work has been supported in part by the Swiss NSF and by the European Union Molnanomag network.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Daniel Loss.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Leuenberger, M., Loss, D. Quantum computing in molecular magnets. Nature 410, 789–793 (2001). https://doi.org/10.1038/35071024

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/35071024

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing