结合高效BB84协议的差分密钥分发系统

A Differential Phase Shift Key Distribution QKD System Combing with Efficient BB84 Scheme

提出一种新的相位编码方案,使用差分和高效BB84协议实现量子密钥分发.在保留差分编码优势的同时,此方案进一步增加系统的安全性.Alice端随机选择{0,π/2,π,3π/2}中的相位对信号脉冲进行调制,Bob端随机选择{0,π/2}中的相位对信号脉冲进行调制.为了提高成码率和简化系统,以η(η→1)的概率选取{0,π}基对相位进行调制,此时系统运行差分编码,用于生成密钥;以(1-η)的概率选取{π/2,3π/2}基中的相位对脉冲信号进行调制.{π/2,3π/2}基的选用是为了增加系统维度和进行安全性评估,不用于生成密钥.设计相应的系统,利用微弱相干光脉冲在该新协议下进行编码,在接收端采用法拉第-迈克尔逊方式进行解码,在实验上实现了长期稳定的密钥分发,误码率<5%,传输距离达85km.

A novel phase modulated quantum key distribution scheme with high security,which is combined differential phase shift quantum key distribution （DPS-QKD） with efficient BB84 scheme, is proposed. Alice chooses phase in {0,π/2,π,3π/2} randomly to modulate the phase of signal pulses and Bob do it in {0,π/2}. The system is designed to demonstrate its feasibility, which features perfect stability with a QBER less than 5% during 85-km fiber transmission.