量子密码通信的信号发送与处理系统

Signal Processing System for Quantum Cryptography

自行研制了一套用于量子密码通信的信号发送与处理系统。该系统将自制的半导体激光器驱动电路、相位调制器驱动电路、单光子探测器电路、数据处理及计算机通讯等电路连接起来 。

Quantum cryptography is a new method for secret communi cation in which the security of the key for messages transmitted by the sender t o the receiver is assured by the inviolability of the uncertainty principle. An all-fiber quantum cryptography system operating at 850 nm is disigned and im plemented based on phase modulated single photon interference, the first in C hina. The transmission distance achieved is 1.1 km, which is only limited by the length of fiber available. The signal transmission and processing system of the quantum key distribution system is presented in detail, including the phase mod ul ator drive circuit, single photon detectors, data sampling and processing circui ts, and system synchronizing circuits.The data transmission rate obtained so far is 3 bits/s, though the maximum rate could be 1 MHz. The measured bit error ra te is lower than 0.1 under stable conditions.