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Experimental demonstration of memory-enhanced scaling for entanglement connection of quantum repeater segments

Abstract

The quantum repeater protocol is a promising approach for implementing long-distance quantum communication and large-scale quantum networks. A key idea of the quantum repeater protocol is to use long-lived quantum memories to achieve an efficient entanglement connection between different repeater segments, with polynomial scaling. Here, we report an experiment that realizes the efficient connection of two quantum repeater segments via on-demand entanglement swapping through the use of two atomic quantum memories with storage times of tens of milliseconds. With the memory enhancement, acceleration in the scaling is demonstrated in the rate for a successful entanglement connection. Experimental realization of the entanglement connection of two quantum repeater segments with an efficient memory-enhanced scaling demonstrates a key advantage of the quantum repeater protocol, creating a cornerstone for the development of future large-scale quantum networks.

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Fig. 1: The quantum repeater protocol and the experimental set-up.
Fig. 2: The quantum repeater node with long memory time.
Fig. 3: Entanglement connection of two quantum repeater segments.
Fig. 4: Memory-enhanced scaling of efficiencies for entanglement connection.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The code used for quantum state tomography is available from the corresponding author upon reasonable request.

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Acknowledgements

This work was supported by the National Key Research and Development Program of China (2016YFA0301902), the Beijing Academy of Quantum Information Sciences, the Frontier Science Center for Quantum Information of the Ministry of Education of China and the Tsinghua University Initiative Scientific Research Program. Y.K.W. acknowledges support from the Shuimu Tsinghua Scholar Program and the International Postdoctoral Exchange Fellowship Program.

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Contributions

L.-M.D. designed the experiment and supervised the project. Y.-F.P., S.Z., N.J., W.C. and C.L. performed the experiment. Y.-F.P. and S.Z. analysed the data. Y.-K.W. contributed materials and analysis tools. Y.-F.P., S.Z., Y.-K.W. and L.-M.D. wrote the manuscript.

Corresponding author

Correspondence to Lu-Ming Duan.

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The authors declare no competing interests.

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Peer review information Nature Photonics thanks Bing Qi and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Six sections and Figs. 1–6.

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Pu, YF., Zhang, S., Wu, YK. et al. Experimental demonstration of memory-enhanced scaling for entanglement connection of quantum repeater segments. Nat. Photonics 15, 374–378 (2021). https://doi.org/10.1038/s41566-021-00764-4

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