Experimental quantum key distribution with double protocol
Hu Hua-Peng, Jing Zhang, Jindong Wang, Huang Yu-Xian, Lu Yi-Qun, Songhao Liu, Wei Lü, (1)华南师范大学信息光电子科技学院,光子信息技术广东省高校重点实验室,广州 510006; (2)中国科学院合肥智能研究所，合肥 230031 · Acta Physica Sinica · 2008
We propose one kind of improved QKD scheme based on time coding and phase coding. The pulse which had been discarded on the BB84 protocol phase coding QKD system is used to realize the time coding protocol, thus the useful bits rate in the present scheme can be doubled. At the same time, the phase coding keys and the time coding keys are obtained, we may combine both as new keys which can enhancethe generated rate and the sensitivity of monitor. At Bob’s side, a Fraday-Michelson is used instead of a traditional M-Z interferometer, which improves the stability of the interference visibility. With the proposed experimental setup, a stable quantum key distribution was performed over 90 km fiber. It is shown in our experiment that the characteristics of our system are as follows: secure, stable and economical.