量子密码通信中量子比特率理论分析

Theoretical Analysis of Quantum Bit Rate in Quantum Cryptography

在量子密钥分配中,量子比特率是一个重要的系统参数。通过引入测量因子和筛选因子,建立了基于理想单光子源和泊松分布单光子源的量子比特率理论模型,给出了量子比特率的表达式,并对两种单光子源进行了比较分析。结果表明,当平均光子数大于1时,泊松分布单光子源能被优化。在发射机脉冲重复率一定的条件下,采用泊松分布单光子源无法达到理想单光子源的量子比特率,这是为保密通信所必须付出的代价。

Quantum bit rate is an important operating parameter based on an ideal single-photon source and a single-photon source in quantum key distribution. The theoretical models with Poisson distribution arc established by intrcducing the measuring factor and the shifting factor, and the expressions of quantum bit rate are given. The two single-photon sources are analyzed by comparison. The rcsults show that quantum bit rate based on the ideal single-photon source cannot be obtained when the transmitter pulse repetition rate is definite and the single-photon source with Poisson distribution is used, and this is the price paid for secret communication.