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Entanglement of three quantum memories via interference of three single photons

Abstract

Quantum memory networks as an intermediate stage in the development of a quantum internet1 will enable a number of significant applications2,3,4,5. To connect and entangle remote quantum memories, it is best to use photons. In previous experiments6,7,8,9,10,11,12,13, entanglement of two memory nodes has been achieved via photon interference. Going beyond the state of the art by entangling many quantum nodes at a distance is highly sought after. Here, we report the entanglement of three remote quantum memories via three-photon interference. We employ laser-cooled atomic ensembles and make use of a ring cavity to enhance the overall efficiency of our memory–photon entanglement. By interfering three single photons from three separate set-ups, we create entanglement of three memories and three photons. Then, by measuring the photons and applying feed-forward, we achieve heralded entanglement between the three memories. Our experiment may be employed as a building block to construct larger and complex quantum networks14,15.

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Fig. 1: Experiment layout.
Fig. 2: Characterization of a single entangled atom–photon pair.
Fig. 3: Characterization of the sixfold entanglement |GHZ6〉.
Fig. 4: Characterization of the three-memory entanglement |GHZ3〉.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding

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Acknowledgements

This work was supported by National Key R&D Program of China (no. 2017YFA0303902), Anhui Initiative in Quantum Information Technologies, National Natural Science Foundation of China, and the Chinese Academy of Sciences.

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Authors

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X.-H.B. and J.-W.P. conceived and designed the experiment. B.J. and X.-J.W. mainly carried out the experiment and collected the data with assistance from all other authors. B.J., X.-J.W. and X.-H.B. analysed the data. B.J., X.-J.W., X.-H.B. and J.-W.P. wrote the paper with input from all other authors. X.-H.B. and J.-W.P. supervised the whole project.

Corresponding authors

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

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The authors declare no competing interests.

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Jing, B., Wang, XJ., Yu, Y. et al. Entanglement of three quantum memories via interference of three single photons. Nature Photon 13, 210–213 (2019). https://doi.org/10.1038/s41566-018-0342-x

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