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Nature. 2017 Sep 7;549(7670):43-47. doi: 10.1038/nature23655. Epub 2017 Aug 9.

Satellite-to-ground quantum key distribution.

Liao SK1,2, Cai WQ1,2, Liu WY1,2, Zhang L2,3, Li Y1,2, Ren JG1,2, Yin J1,2, Shen Q1,2, Cao Y1,2, Li ZP1,2, Li FZ1,2, Chen XW1,2, Sun LH1,2, Jia JJ3, Wu JC3, Jiang XJ4, Wang JF4, Huang YM5, Wang Q5, Zhou YL6, Deng L6, Xi T7, Ma L8, Hu T9, Zhang Q1,2, Chen YA1,2, Liu NL1,2, Wang XB2, Zhu ZC6, Lu CY1,2, Shu R2,3, Peng CZ1,2, Wang JY2,3, Pan JW1,2.

Author information

Department of Modern Physics and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
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.
Key Laboratory of Space Active Opto-Electronic Technology, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China.
Key Laboratory of Optical Engineering, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China.
Shanghai Engineering Center for Microsatellites, Shanghai 201203, China.
State Key Laboratory of Astronautic Dynamics, Xi'an Satellite Control Center, Xi'an 710061, China.
Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, China.
National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China.


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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