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.

Unconditional room-temperature quantum memory

Abstract

Just as classical information systems require buffers and memory, the same is true for quantum information systems. The potential that optical quantum information processing holds for revolutionizing computation and communication is therefore driving significant research into developing optical quantum memory. A practical optical quantum memory must be able to store and recall quantum states on demand with high efficiency and low noise. Ideally, the platform for the memory would also be simple and inexpensive. Here, we present a complete tomographic reconstruction of quantum states that have been stored in the ground states of rubidium in a vapour cell operating at around 80 °C. Without conditional measurements, we show recall fidelity up to 98% for coherent pulses containing around one photon. To unambiguously verify that our memory beats the quantum no-cloning limit we employ state-independent verification using conditional variance and signal-transfer coefficients.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Quadrature measurements as a function of local oscillator phase.
Figure 2: Density matrix elements for two sets of input and output pulses.
Figure 3: Photon-number statistics and Wigner functions.
Figure 4: Fidelity and TV benchmarks.

Similar content being viewed by others

References

  1. Niskanen, A. O. et al. Quantum coherent tunable coupling of superconducting qubits. Science 316, 723–726 (2007).

    Article  ADS  Google Scholar 

  2. Petta, J. R. et al. Coherent manipulation of coupled electron spins in semiconductor quantum dots. Science 309, 2180–2184 (2005).

    Article  ADS  Google Scholar 

  3. Home, J. P. et al. Complete methods set for scalable ion trap quantum information processing. Science 325, 1227–1230 (2009).

    Article  ADS  MathSciNet  Google Scholar 

  4. Gisin, N., Ribordy, G., Tittel, W. & Zbinden, H. Quantum cryptography. Rev. Mod. Phys. 74, 145–195 (2002).

    Article  ADS  Google Scholar 

  5. Monroe, C. et al. Demonstration of a fundamental quantum logic gate. Phys. Rev. Lett. 75, 4714–4717 (1995).

    Article  ADS  MathSciNet  Google Scholar 

  6. Grosshans, F. & Grangier, P. Quantum cloning and teleportation criteria for continuous quantum variables. Phys. Rev. A 64, 010301 (2001).

    Article  ADS  MathSciNet  Google Scholar 

  7. Cerf, N. J., Kruger, O., Navez, P., Werner, R. F. & Wolf, M. M. Non-gaussian cloning of quantum coherent states is optimal. Phys. Rev. Lett. 95, 070501 (2005).

    Article  ADS  Google Scholar 

  8. Zhang, R., Garner, S. R. & Hau, L. V. Creation of long-term coherent optical memory via controlled nonlinear interactions in Bose–Einstein condensates. Phys. Rev. Lett. 103, 233602 (2009).

    Article  ADS  Google Scholar 

  9. Jin, X-M. et al. Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory. Preprint at http://arxiv.org/abs/1004.4691v1 (2010).

  10. Choi, K. S., Deng, H., Laurat, J. & Kimble, H. J. Mapping photonic entanglement into and out of a quantum memory. Nature 452, 67–71 (2008).

    Article  ADS  Google Scholar 

  11. Choi, K. S., Goban, A., Papp, S. B., van Enk, S. J. & Kimble, H. J. Entanglement of spin waves among four quantum memories. Nature 468, 412–416 (2010).

    Article  ADS  Google Scholar 

  12. Hedges, M., Longdell, J., Li, Y. & Sellars, M. Efficient quantum memory for light. Nature 465, 1052–1056 (2010).

    Article  ADS  Google Scholar 

  13. Saglamyurek, E. et al. Broadband waveguide quantum memory for entangled photons. Nature 469, 512–515 (2011).

    Article  ADS  Google Scholar 

  14. Clausen, C. et al. Quantum storage of photonic entanglement in a crystal. Nature 469, 508–511 (2011).

    Article  ADS  Google Scholar 

  15. van der Wal, C. H. et al. Atomic memory for correlated photon states. Science 301, 196–200 (2003).

    Article  ADS  Google Scholar 

  16. Julsgaard, B., Sherson, J., Cirac, J., Fiurasek, J. & Polzik, E. Experimental demonstration of quantum memory for light. Nature 432, 482–486 (2004).

    Article  ADS  Google Scholar 

  17. Appel, J., Figueroa, E., Korystov, D., Lobino, M. & Lvovsky, A. I. Quantum memory for squeezed light. Phys. Rev. Lett. 100, 093602 (2008).

    Article  ADS  Google Scholar 

  18. Honda, K. et al. Storage and retrieval of a squeezed vacuum. Phys. Rev. Lett. 100, 093601 (2008).

    Article  ADS  Google Scholar 

  19. Eisaman, M. D. et al. Electromagnetically induced transparency with tunable single-photon pulses. Nature 438, 837–841 (2005).

    Article  ADS  Google Scholar 

  20. Moiseev, S. A. & Kroll, S. Complete reconstruction of the quantum state of a single-photon wave packet absorbed by a doppler-broadened transition. Phys. Rev. Lett 87, 173601 (2001).

    Article  ADS  Google Scholar 

  21. Longdell, J. J., Hétet, G., Lam, P. K. & Sellars, M. J. Analytic treatment of controlled reversible inhomogeneous broadening quantum memories for light using two-level atoms. Phys. Rev. A 78, 032337 (2008).

    Article  ADS  Google Scholar 

  22. Alexander, A. L., Longdell, J. J. & Sellars, M. J. Measurement of the ground-state hyperfine coherence time of 151Eu3+:Y2SiO5 . J. Opt. Soc. Am. B 24, 2479–2482 (2007).

    Article  ADS  Google Scholar 

  23. Nunn, J. et al. Multimode memories in atomic ensembles. Phys. Rev. Lett. 101, 260502 (2008).

    Article  ADS  Google Scholar 

  24. Hétet, G., Longdell, J. J., Sellars, M. J., Lam, P. K. & Buchler, B. C. Multimodal properties and dynamics of gradient echo quantum memory. Phys. Rev. Lett. 101, 203601 (2008).

    Article  ADS  Google Scholar 

  25. Hétet, G., Longdell, J. J., Alexander, A. L., Lam, P. K. & Sellars, M. J. Electro-optic quantum memory for light using two-level atoms. Phys. Rev. Lett. 100, 023601 (2008).

    Article  ADS  Google Scholar 

  26. Hétet, G. et al. Photon echoes generated by reversing magnetic field gradients in a rubidium vapor. Opt. Lett. 33, 2323–2325 (2008).

    Article  ADS  Google Scholar 

  27. Hosseini, M., Sparkes, B. M., Campbell, G., Buchler, B. C. & Lam, P. K. High efficiency coherent optical memory with warm rubidium vapour. Nat. Commun. 2, 1–5 (2011).

    Article  Google Scholar 

  28. Hosseini, M. et al. Coherent optical pulse sequencer for quantum applications. Nature 461, 241–245 (2009).

    Article  ADS  Google Scholar 

  29. Buchler, B. C., Hosseini, M., Hétet, G., Sparkes, B. M. & Lam, P. K. Precision spectral manipulation of optical pulses using a coherent photon echo memory. Opt. Lett. 35, 1091–1093 (2010).

    Article  ADS  Google Scholar 

  30. Rehàcek, J., Hradil, Z. & Jezek, M. Iterative algorithm for reconstruction of entangled states. Phys. Rev. A 63, 040303 (2002).

    Article  MathSciNet  Google Scholar 

  31. Walls, D. & Milburn, G. Quantum Optics (Springer, 1994).

    Book  Google Scholar 

  32. Jeong, H., Ralph, T. C. & Bowen, W. P. Quantum and classical fidelity for guassian states. J. Opt. Soc. Am. B 24, 355–362 (2007).

    Article  ADS  Google Scholar 

  33. Jeong, H., Ralph, T. C. & Bowen, W. P. Quantum and classical fidelities for Gaussian states. J. Opt. Soc. Am. B 24, 355–362 (2007).

    Article  ADS  MathSciNet  Google Scholar 

  34. Poizat, J-P., Roch, J-F. & Grangier, P. Characterization of quantum non-demolition measurements in optics. Ann. Phys. Fr. 19, 265–297 (1994).

    Article  ADS  Google Scholar 

  35. Ralph, T. C. & Lam, P. K. Teleportation with bright squeezed light. Phys. Rev. Lett. 81, 5668–5671 (1998).

    Article  ADS  Google Scholar 

  36. Bowen, W. et al. Experimental investigation of continuous-variable quantum teleportation. Phys. Rev. A 67, 032302 (2003).

    Article  ADS  Google Scholar 

  37. Hétet, G., Peng, A., Johnsson, M. T., Hope, J. J. & Lam, P. K. Characterization of electromagnetically-induced-transparency-based continuous-variable quantum memories. Phys. Rev. A 77, 012323 (2008).

    Article  ADS  Google Scholar 

  38. Ortalo, J. et al. Atomic-ensemble-based quantum memory for sideband modulations. J. Phys. B 42, 114010 (2009).

    Article  ADS  Google Scholar 

  39. Balabas, M. V. et al. High quality anti-relaxation coating material for alkali atom vapor cells. Opt. Exp. 18, 5825–5830 (2010).

    Article  ADS  Google Scholar 

  40. Kubler, H., Shaffer, J. P., Baluktsian, T., Low, R. & Pfau, T. Coherent excitation of Rydberg atoms in micrometre-sized atomic vapour cells. Nature Photon. 4, 112–116 (2010).

    Article  ADS  Google Scholar 

  41. Eklunda, E. J., Shkela, A. M., Knappeb, S., Donleyb, E. & Kitching, J. Glass-blown spherical microcells for chip-scale atomic devices. Sens. Actuat. A 143, 175–180 (2008).

    Article  Google Scholar 

  42. Yang, W. et al. Atomic spectroscopy on a chip. Nature Photon. 1, 331–335 (2007).

    Article  ADS  Google Scholar 

  43. Baluktsian, T. et al. Fabrication method for microscopic vapor cells for alkali atoms. Opt. Lett. 35, 1950–1952 (2010).

    Article  ADS  Google Scholar 

  44. Wu, B. et al. Slow light on a chip via atomic quantum state control. Nature Photon. 4, 776–779 (2010).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

The authors thank J. Bernu for providing us with a Matlab code to carry out maximum-likelihood reconstruction and G. Hétet, M. Sellars and T. Ralph for discussions. This research was conducted by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology (project number CE110001027).

Author information

Authors and Affiliations

Authors

Contributions

Experiments, measurements and data analysis were carried out by M.H. with the assistance of B.M.S. and G.C. for data collection and experimental preparation. The project was planned and supervised by B.C.B. and P.K.L. The manuscript was written by M.H., B.C.B. and G.C. with the assistance of all other authors.

Corresponding author

Correspondence to B. C. Buchler.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 717 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Hosseini, M., Campbell, G., Sparkes, B. et al. Unconditional room-temperature quantum memory. Nature Phys 7, 794–798 (2011). https://doi.org/10.1038/nphys2021

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphys2021

This article is cited by

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