A stable long-distance quantum key distribution system
Guang Ming Wu, Zhou Chun-Yuan, Chen Xiu-Liang, Han Xiao-Hong, Zeng Heping, 华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海 200062 · Acta Physica Sinica · 2005
A stable long-distance quantum key distribution system which has been just completed in our laboratory is demonstrated in this paper. The idea of “plug and pl ay" was adopted to automatically compensate the polarization mode dispersion and phase shift. A symmetrical capacitance-balance technique and magic-T network were used in the single-photon detection module, wherein a detection efficiency of more than 5% and a dark count probability of lower than 29×10-6/p ulse were achieved. As a result, we have realized stable (longer than 12 h) quantum k ey distribution experiment in 506 km single mode fiber with mean photon number of 007 and quantum bit error rate of 4%.