Abstract

Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD—a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

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Acknowledgements

We thank many colleagues at the National Space Science Center, especially B.-M. Xu, J. Li, J.-C. Gong, B. Chen and J. Liu for their management and coordination. We thank X.-F. Ma, C. Jiang, L. Li, X.-M. Zhang and Y.-W. Chen for discussions. This work was supported by the Strategic Priority Research Program on Space Science, Chinese Academy of Sciences, and the National Natural Science Foundation of China.

Author information

Affiliations

  1. Department of Modern Physics and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China

    • Sheng-Kai Liao
    • , Wen-Qi Cai
    • , Wei-Yue Liu
    • , Yang Li
    • , Ji-Gang Ren
    • , Juan Yin
    • , Qi Shen
    • , Yuan Cao
    • , Zheng-Ping Li
    • , Feng-Zhi Li
    • , Xia-Wei Chen
    • , Li-Hua Sun
    • , Qiang Zhang
    • , Yu-Ao Chen
    • , Nai-Le Liu
    • , Chao-Yang Lu
    • , Cheng-Zhi Peng
    •  & Jian-Wei Pan
  2. Chinese Academy of Sciences (CAS) Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China

    • Sheng-Kai Liao
    • , Wen-Qi Cai
    • , Wei-Yue Liu
    • , Liang Zhang
    • , Yang Li
    • , Ji-Gang Ren
    • , Juan Yin
    • , Qi Shen
    • , Yuan Cao
    • , Zheng-Ping Li
    • , Feng-Zhi Li
    • , Xia-Wei Chen
    • , Li-Hua Sun
    • , Qiang Zhang
    • , Yu-Ao Chen
    • , Nai-Le Liu
    • , Xiang-Bin Wang
    • , Chao-Yang Lu
    • , Rong Shu
    • , Cheng-Zhi Peng
    • , Jian-Yu Wang
    •  & Jian-Wei Pan
  3. Key Laboratory of Space Active Opto-Electronic Technology, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China

    • Liang Zhang
    • , Jian-Jun Jia
    • , Jin-Cai Wu
    • , Rong Shu
    •  & Jian-Yu Wang
  4. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China

    • Xiao-Jun Jiang
    •  & Jian-Feng Wang
  5. Key Laboratory of Optical Engineering, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China

    • Yong-Mei Huang
    •  & Qiang Wang
  6. Shanghai Engineering Center for Microsatellites, Shanghai 201203, China

    • Yi-Lin Zhou
    • , Lei Deng
    •  & Zhen-Cai Zhu
  7. State Key Laboratory of Astronautic Dynamics, Xi’an Satellite Control Center, Xi’an 710061, China

    • Tao Xi
  8. Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, China

    • Lu Ma
  9. National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China

    • Tai Hu

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Contributions

C.-Z.P. and J.-W.P. conceived the research. C.-Z.P., J.-Y.W. and J.-W.P. designed the experiments. S.-K.L., W.-Q.C., Y.L., C.-Z.P. and J.-W.P. developed the spaceborn QKD source. S.-K.L., W.-Q.C., L.Z., J.Y., J.-J.J., J.-C.W., L.D., Y.-L.Z., Z.-C.Z., R.S., C.-Z.P., J.-Y.W. and J.-W.P. designed and developed the satellite and payloads. S.-K.L., L.Z., J.-J.J., R.S., C.-Z.P. and J.-Y.W. developed the ATP technique. S.-K.L., J.Y., L.Z., C.-Z.P. and J.-W.P. developed the polarization compensation method. X.-B.W. contributed to the decoy-state analysis. C.-Y.L., C.-Z.P. and J.-W.P. analysed the data and wrote the manuscript, with input from S.-K.L., W.-Y.L., Q.S., Y.L. and F.-Z.L. All authors contributed to the data collection, discussed the results and reviewed the manuscript. J.-W.P. supervised the whole project.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Cheng-Zhi Peng or Jian-Yu Wang or Jian-Wei Pan.

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https://doi.org/10.1038/nature23655

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