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Experimental demonstration of non-bilocality with truly independent sources and strict locality constraints

Nature Photonics volume 13, pages 687–691 (2019)Cite this article

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Abstract

The ongoing interest in creating a secure global quantum network culminated recently in the demonstration of transcontinental quantum communication1. There is a pressing need to examine the properties attached to a quantum network architecture from multiple perspectives, including physics foundations2, communication security3, the efficient use of resources and innovative technological applications4,5. Here, we present an experimental realization of a five-node quantum network, in which quantum sources at two nodes deliver entangled photon pairs to three measurement nodes. With relevant events between five nodes separated space-like, we demonstrate violation of the Bell inequality and bilocal inequality6, with the locality, measurement independence and quantum source independence loopholes closed simultaneously in a quantum network. This experimental realization may be valuable for the design and implementation of future quantum networks.

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Fig. 1: Space–time diagram of the simplest quantum network.
Fig. 2: Schematics for testing the bilocality in a network.
Fig. 3: Space–time configuration of relevant events in each experimental trial.
Fig. 4: \({\cal{B}}_{13}\) and \(\cal{S}\) versus noise parameter p.

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.

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Acknowledgements

We thank Y. Liu, Y. Li and Y.-Q. Nie for enlightening discussions, Y.-L. Mao for assistance, K.-X. Yang for help with the aerial photographs and Quantum Ctek for providing the components used in the QRNGs. This work was supported by the National Key R&D Program of China (2017YFA0303900, 2017YFA0304000), the National Natural Science Foundation of China and the Chinese Academy of Sciences.

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Author notes

  1. These authors contributed equally: Qi-Chao Sun, Yang-Fan Jiang, Bing Bai.

Authors and Affiliations

  1. National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, Shanghai Branch, University of Science and Technology of China, Shanghai, China

    Qi-Chao Sun, Yang-Fan Jiang, Bing Bai, Xiao Jiang, Jun Zhang, Qiang Zhang, Jingyun Fan & Jian-Wei Pan

  2. CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, Shanghai Branch, University of Science and Technology of China, Shanghai, China

    Qi-Chao Sun, Yang-Fan Jiang, Bing Bai, Xiao Jiang, Jun Zhang, Qiang Zhang, Jingyun Fan & Jian-Wei Pan

  3. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China

    Weijun Zhang, Hao Li, Lixing You & Zhen Wang

  4. Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China

    Xianfeng Chen

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Contributions

Q.-C.S., Q.Z., J.F. and J.-W.P. conceived and designed the experiments. B.B. and J.Z. built the QRNGs. W.Z., H.L., L.Y. and Z.W. fabricated the SNSPDs. Q.-C.S. and Y.-F.J. built the experimental network and carried out the experiment. X.J. and X.C. provided experimental assistance. Q.-C.S. and Y.-F.J. analysed the data. Q.-C.S., Q.Z., J.F. and J.-W.P. wrote the manuscript, with input from all authors.

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Correspondence to Qiang Zhang, Jingyun Fan or Jian-Wei Pan.

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Sun, QC., Jiang, YF., Bai, B. et al. Experimental demonstration of non-bilocality with truly independent sources and strict locality constraints. Nat. Photonics 13, 687–691 (2019). https://doi.org/10.1038/s41566-019-0502-7

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