背景光对星地量子密钥分配量子误码率的影响

量子误码率是量子密钥分配系统的重要参数之一.对于星地量子密钥分配,采用具有泊松分布的高度衰减激光脉冲作为单光子源,建立了由背景光引起的量子误码率理论模型,给出了量子误码率的表达式.针对轨道高度为300km的低轨卫星-地面站间链路,进行了数值仿真分析.研究表明,背景光是限制自由空间量子密钥分配链路距离的主要因素之一,在低轨卫星-地面站间进行量子密钥分配是可行的.在白天,量子误码率的量级为10-3～10-2;在夜晚,满月时为10-4,新月时为10-6～10-5.

Influence of background light on quantum bit error rate in satellite-to-ground quantum key distribution

Quantum bit error rate is an important operating parameter in quantum key distribution. As to the satellite-to-ground quantum key distribution, the highly attenuated laser pulses with Poisson distribution are used as single-photon sources. The theoretical model of the quantum bit error rate caused by the background light is established and the expressions of the quantum bit error rate are given. The quantum bit error rate is analyzed in the numerical simulation for the laser links between a ground station and a 300km altitude satellite in a low earth orbit. The study shows that the background light is one of the main factors that limit the link distance for free-space quantum key distribution, and that it is feasible to implement quantum key distribution between a ground station and a satellite in a low earth orbit. In daylight, the quantum bit error rate is on the order of 10^-3-10^-2, at night, 10^-4 during a full moon and 10^-6-10^-5 during a new moon.