Space-to-Ground Quantum Key Distribution Using a Small-Sized Payload on Tiangong-2 Space Lab
Sheng-Kai Liao, Jin Lin, Ji-Gang Ren, Wei-Yue Liu, Jia Qiang, Juan Yin, Yang Li, Qi Shen, Liang Zhang, Xue-Feng Liang, Hai-Lin Yong, Feng-Zhi Li, Ya-Yun Yin, Yuan Cao, Wen-Qi Cai, Wen-Zhuo Zhang, Jian-Jun Jia, Jin-Cai Wu, Xiao-Wen Chen, Shan-Cong Zhang, Xiao-Jun Jiang, Jian-Feng Wang, Yong-Mei Huang, Qiang Wang, Lu Ma, Li Li, Ge-Sheng Pan, Qiang Zhang, Yu-Ao Chen, Chao-Yang Lu, Nai-Le Liu, Xiongfeng Ma, Rong Shu, Cheng-Zhi Peng, Jian-Yu Wang, Jian-Wei Pan
Chin. Phys. Lett.
2017, 34 (9):
090302
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DOI: 10.1088/0256-307X/34/9/090302
Quantum technology establishes a foundation for secure communication via quantum key distribution (QKD). In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50 MHz vacuum + weak decoy-state optical source is sent through a reflective telescope with an aperture of 200 mm. On the ground station, a telescope with an aperture of 1200 mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100 bps with a communication distance up to 719 km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.