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对一种结合离散调制和反向协调,适用于长距离传输的连续变量量子密钥分发四态协议的安全性进行了严格证明.这种协议中Alice发送的态与高斯调制协议中的有一定差异,这种差异可以等价成信道衰减和额外噪声.另外,由于Alice不可能做到精确调制,这会导致其发送的相干态中含有噪声.把这种调制引起的噪声看作光源的噪声,并推导出了在光源噪声不能被窃听者所利用的条件下的安全码率的下界.为了避免实验上快速、随机的控制本地振荡光的相位,还将无开关协议和四态协议相结合,分析了其安全性.
A rigorous proof of the security of a four-state protocol for quantum-key distribution with continuous variables that is suitable for long-haul transmission in combination with discrete modulation and backward co-ordination is given in Alice’s state of transmission and Gaussian modulation protocol Difference, this difference can be equivalent to the channel attenuation and additional noise.In addition, because Alice can not be precise modulation, which will lead to the coherent state of its transmitted noise. The noise caused by this modulation as the light source noise , And deduced the lower bound of the safe bit rate in the condition that the light source noise can not be used by the eavesdropper. In order to avoid experimentally controlling the phase of the local oscillation light rapidly and randomly, a switchless protocol and a four-state protocol are also combined , Analyzed its security.