Adaptive continuous variable quantum key distribution based on channel estimation
基于信道估计的自适应连续变量量子密钥分发方法

In order to obtain steady key rate for a continuous variable quantum key distribution system, Alice should adaptively adjust the intensity of optical pulses she sents. In this paper, an optical fiber channel is taken as the additive bosonic quantum Gaussian channel. It is proven that a Gaussian channel transforms Gaussian states into Gaussian states. The maximum-likelihood method is used to estimate the channel parameters after balanced homodyne detection. Then, Alice can change the intensity of optical pulses adaptively according to the estimated noise level, thereby a steady key rate can be obtained.