基于单脉冲多位编码的全光纤连续变量量子密钥分发

An All-Fiber Continuous Variable Quantum Key Distribution Based on Multi-bits Coding of Single Pulse

实现了一种基于单脉冲多位编码的离散调制连续变量量子密钥分发方案。该方案利用时分复用和偏振复用相结合的方式进行远距离光纤传输。实验光源采用脉宽为200ns,重复频率为1 MHz的准连续光。该准连续光的每一个光脉冲在时域上被分为四等份。对每小份都编码两个正交分量,从而增大了密钥率。在25 km光纤传输时,整套系统的安全码率为32.8 kbit/s。

An all-fiber continuous variable quantum key distribution by implementing discrete-modulated coherent state protocol based on multi-bits coding of single pulse is realized. The system employs a scheme combining polarization and frequency multiplexing. The pulse width of quasi-continuous wave is 200 ns. Each pulse is divided into four equal parts in time domain. In order to increase the secure key rate, the two quadrature components of each part are encoded with random number. At a repetition rate of 1MHz, the system achieves a final secure key rate of 32.8kb/s over a distance of 25 km of optical fiber.