Letter | Published:

Efficient and long-lived quantum memory with cold atoms inside a ring cavity

Nature Physics volume 8, pages 517521 (2012) | Download Citation

Abstract

Quantum memories are regarded as one of the fundamental building blocks of linear-optical quantum computation1 and long-distance quantum communication2. A long-standing goal to realize scalable quantum information processing is to build a long-lived and efficient quantum memory. There have been significant efforts distributed towards this goal. However, either efficient but short-lived3,4 or long-lived but inefficient quantum memories5,6,7 have been demonstrated so far. Here we report a high-performance quantum memory in which long lifetime and high retrieval efficiency meet for the first time. By placing a ring cavity around an atomic ensemble, employing a pair of clock states, creating a long-wavelength spin wave and arranging the set-up in the gravitational direction, we realize a quantum memory with an intrinsic spin wave to photon conversion efficiency of 73(2)% together with a storage lifetime of 3.2(1) ms. This realization provides an essential tool towards scalable linear-optical quantum information processing.

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Acknowledgements

This work was supported by the European Commission through the ERC Grant, the STREP project HIP, the CAS, the NNSFC and the National Fundamental Research Program (Grant No. 2011CB921300) of China.

Author information

Affiliations

  1. Physikalisches Institut der Universitaet Heidelberg, Philosophenweg 12, Heidelberg 69120, Germany

    • Xiao-Hui Bao
    • , Andreas Reingruber
    • , Peter Dietrich
    • , Alexander Dück
    • , Thorsten Strassel
    •  & Jian-Wei Pan
  2. National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China

    • Xiao-Hui Bao
    • , Jun Rui
    • , Li Li
    • , Nai-Le Liu
    • , Bo Zhao
    •  & Jian-Wei Pan

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Contributions

X-H.B., A.D., B.Z. and J-W.P. conceived and designed the experiment. A.D., P.D., A.R., T.S. and X-H.B. built the set-up. X-H.B., A.R., P.D. and J.R. carried out the experiment. X-H.B., A.R., L.L., N-L.L. and B.Z. analysed the data. X-H.B. and B.Z. wrote the paper with substantial contributions by all authors. J-W.P. supervised the whole project.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Bo Zhao or Jian-Wei Pan.

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DOI

https://doi.org/10.1038/nphys2324

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