Letter

Experimental nested purification for a linear optical quantum repeater

Received:
Accepted:
Published online:

Abstract

Quantum repeaters1,2,3,4 are essential elements for demonstrating global-scale quantum communication. Over the past few decades, tremendous efforts have been dedicated to implementing a practical quantum repeater5,6,7,8,9,10. However, nested purification1, the backbone of a quantum repeater, remains a challenge because the capacity for successive entanglement manipulation is still absent. Here, we propose and demonstrate an architecture of nested purification using spontaneous parametric downconversion sources11. A heralded entangled photon pair with higher fidelity is successfully purified from two copies of low-fidelity pairs that experience entanglement swapping and noisy channels. By delicately designing the optical circuits, double-pair emission noise is eliminated automatically and the purified state can be used for scalable entanglement connections to extend the communication distance. Combined with a quantum memory, our approach can be applied immediately in the implemention of a practical quantum repeater.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (grants nos. 11274292, 11374284, 11425417, 11521063 and 61625503), the National Fundamental Research Program (grants nos. 2013CB336800 and 2013CB922001) and the Chinese Academy of Sciences.

Author information

Author notes

  1. Luo-Kan Chen, Hai-Lin Yong and Ping Xu contributed equally to this work.

Affiliations

  1. Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, 201315, Shanghai, China

    • Luo-Kan Chen
    • , Hai-Lin Yong
    • , Ping Xu
    • , Xing-Can Yao
    • , Zheng-Da Li
    • , Chang Liu
    • , He Lu
    • , Nai-Le Liu
    • , Li Li
    • , Tao Yang
    • , Cheng-Zhi Peng
    • , Bo Zhao
    • , Yu-Ao Chen
    •  & Jian-Wei Pan
  2. CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, 201315, Shanghai, China

    • Luo-Kan Chen
    • , Hai-Lin Yong
    • , Ping Xu
    • , Xing-Can Yao
    • , Zheng-Da Li
    • , Chang Liu
    • , He Lu
    • , Nai-Le Liu
    • , Li Li
    • , Tao Yang
    • , Cheng-Zhi Peng
    • , Bo Zhao
    • , Yu-Ao Chen
    •  & Jian-Wei Pan
  3. CAS-Alibaba Quantum Computing Laboratory, 201315, Shanghai, China

    • Luo-Kan Chen
    • , Hai-Lin Yong
    • , Ping Xu
    • , Xing-Can Yao
    • , Zheng-Da Li
    • , Chang Liu
    • , He Lu
    • , Nai-Le Liu
    • , Li Li
    • , Tao Yang
    • , Cheng-Zhi Peng
    • , Bo Zhao
    • , Yu-Ao Chen
    •  & Jian-Wei Pan
  4. Department of Physics, Shanghai Jiao Tong University, 200240, Shanghai, China

    • Tong Xiang

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Contributions

B.Z., Y.-A.C. and J.-W.P. conceived and designed the experiments. L.-K.C., P.X. and X.-C.Y. designed and characterized the multiphoton optical circuits. H.-L.Y. and C.L. developed the feedback system. T.X., Z.-D.L., H.L., N.-L.L., L.L., T.Y. and C.-Z.P. provided experimental assistance. L.-K.C., H.-L.Y., P.X., T.X. and Z.D-.L. collected and analysed the data. L.-K.C., X.-C.Y., B.Z., Y.-A.C. and J.-W.P. wrote the manuscript, with input from all authors. N.-L.L., Y.-A.C. and J.-W.P. supervised the project.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Bo Zhao or Yu-Ao Chen or Jian-Wei Pan.

Electronic supplementary material

  1. Supplementary Information

    Supplementary material