An efficient quantum light–matter interface with sub-second lifetime


Quantum repeaters1 hold promise for scalable long-distance quantum communication. The basic building block is a quantum light–matter interface that generates non-classical correlations between light and a quantum memory2. Significant progress has been made in improving the performance of this interface3,4, but further development of quantum repeater is hindered by the difficulty of integrating the key capabilities into a single system4. Here we report a high-performance interface with an efficiency and lifetime that fulfil the requirement of a quantum repeater. By confining cold atoms with a three-dimensional optical lattice and enhancing the atom–photon coupling with a ring cavity, we observe an initial retrieval efficiency of 76 ± 5% together with a 1/e lifetime of 0.22 ± 0.01 s, which supports a sub-Hz entanglement distribution of up to 1,000 km through the Duan-Lukin-Cirac-Zoller (DLCZ) protocol2. Together with an efficient telecom interface5,6 and moderate multiplexing7, our result may enable a quantum repeater system that beats direct transmission in the near future4.

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Figure 1: Experimental set-up and atomic levels.
Figure 2: Lifetime measurement of the optical lattice-trapped EIT memory without a cavity.
Figure 3: Millisecond-regime decay of the retrieval efficiency with DLCZ storage.
Figure 4: Intrinsic retrieval efficiency χ versus storage time for DLCZ storage.


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This work was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, and the National Fundamental Research Program of China. X.-H.B. acknowledge support from the Youth Qianren Program.

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S.-J.Y., X.-H.B. and J.-W.P. conceived and designed the experiment. S.-J.Y., X.-J.W. and X.-H.B. carried out the experiment. All authors analysed the data. S.-J.Y., X.-H.B. and J.-W.P. wrote the paper. X.-H.B. and J.-W.P. supervised the whole project.

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Correspondence to Xiao-Hui Bao or Jian-Wei Pan.

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The authors declare no competing financial interests.

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Yang, S., Wang, X., Bao, X. et al. An efficient quantum light–matter interface with sub-second lifetime. Nature Photon 10, 381–384 (2016).

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