利用无噪线性光放大器增加连续变量量子密钥分发最远传输距离

摘要

Developing quantum key distribution (QKD) protocols that can resist losses and noises is of great importance in practice. We show that the maximum transmission distance and tolerable excess noise of the no-switching CV-QKD protocol can be dramatically increased by using a noiseless linear amplifier (NLA). It is proved that an NLA with a gain g can increase the maximum transmission distance by 20 log10 g km, whereα=0.2 dB/km is the loss coefficient of the fiber channel.α%　　如何提高实际量子密钥分发系统的安全码率和最远传输距离是量子密码学领域重要的研究课题.本文采用量子无噪线性光放大器放大量子信号，以改进连续变量量子密钥分发系统实际性能.经仔细研究，本文发现增益系数为g的线性无噪放大器可将连续变量量子密钥分发系统的最远安全传输距离提高20 log10(g)/a km (a=0.2 dB/km为光纤信道的损耗系数)，并改善系统的安全码率和噪声抗性.