An auto-compensating and efficient differential phase shift quantum key distribution system
自动补偿高效的差分相位编码QKD系统

We present an improved differential phase shift quantum key distribution scheme which features auto-compensation,high efficiency,and excellent practicality.Alice modulates continuous laser using an intensity modulator based on polarization to generate coherent pulse train.Bob employs a Fraday-Michelson interferometer instead of a traditional M-Z interferometer,which automatically compensates for the polarization mode dispersion caused by the changes of environment and improves the stability of the interference visibility.The present scheme not only has a simpler configuration,but also offers a higher key creation efficiency than traditional schemes.Furthermore,it enhances the security of the system.With the proposed experimental setup,a stable quantum key distribution was performed over 80km fiber with a quantum bit-error rate of less than 4%.