4 years ago

Satellite-to-ground quantum key distribution

Jian-Feng Wang, Cheng-Zhi Peng, Nai-Le Liu, Feng-Zhi Li, Zhen-Cai Zhu, Liang Zhang, Xiao-Jun Jiang, Zheng-Ping Li, Rong Shu, Jian-Wei Pan, Tao Xi, Tai Hu, Wen-Qi Cai, Jian-Jun Jia, Yang Li, Yu-Ao Chen, Sheng-Kai Liao, Juan Yin, Lu Ma, Li-Hua Sun, Qiang Wang, Qi Shen, Lei Deng, Xia-Wei Chen, Ji-Gang Ren, Jian-Yu Wang, Yong-Mei Huang, Yi-Lin Zhou, Xiang-Bin Wang, Jin-Cai Wu, Wei-Yue Liu, Qiang Zhang, Yuan Cao, Chao-Yang Lu

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.

Publisher URL: http://dx.doi.org/10.1038/nature23655

DOI: 10.1038/nature23655

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