Decoherence-protected memory for a single-photon qubit

  • Nature Photonicsvolume 12pages1821 (2018)
  • doi:10.1038/s41566-017-0050-y
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Distributed quantum computation in a quantum network1,2,3 is based on the idea that qubits can be preserved and efficiently exchanged between long-lived, stationary network nodes via photonic links4. Although long qubit lifetimes have been observed5,6,7,8,9,10, and non-qubit excitations have been memorized11,12,13,14, the long-lived storage and efficient retrieval of a photonic qubit by means of a light–matter interface15,16,17,18,19,20 remains an outstanding challenge. Here, we report on a qubit memory based on a single atom coupled to a high-finesse optical resonator. By mapping the qubit between an interface basis with strong light–matter coupling and a memory basis with low decoherence, we achieve a coherence time exceeding 100 ms with a time-independent storage-and-retrieval efficiency of 22%. The former constitutes an improvement by two orders of magnitude21,22 and thus implements an efficient photonic qubit memory with a coherence time that exceeds the lower bound needed for direct qubit teleportation in a global quantum internet.

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We thank B. Wang for the development of the hardware and S. Dürr, L. Li and M. Uphoff for discussion. This work was supported by the Bundesministerium für Bildung und Forschung via the Verbund Q.comand by the Deutsche Forschungsgemeinschaft via the excellence cluster Nanosystems Initiative Munich (NIM).

Author information

Author notes

    • A. Neuzner

    Present address: OHB System AG, Weβling, Germany

    • S. Ritter

    Present address: TOPTICA Photonics AG, Graefelfing, Germany

  1. M. Körber and O. Morin contributed equally to this work.


  1. Max-Planck-Institut für Quantenoptik, Garching, Germany

    • M. Körber
    • , O. Morin
    • , S. Langenfeld
    • , A. Neuzner
    • , S. Ritter
    •  & G. Rempe


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M.K., O.M., A.N., S.R. and G.R. conceived the experiment. M.K., O.M. and S.L. performed the experiment. M.K., O.M., S.L., S.R. and G.R. evaluated the data. All authors contributed to the writing of the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to M. Körber.

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