量子密钥误码系数分析及对密钥分配的影响

Analysis of the coefficient of QBER and its influence

分析了基于微弱相干脉冲量子密钥分配的误码系数,结果表明,误码系数并非为一固定常数,而是随着传输距离增加而变化。根据实验数据对误码系数与传输距离之间的关系进行了函数拟合,3个实验小组数据拟合出能够很好地符合同一指数函数形式。利用拟合的误码系数对诱惑态下BB84量子密钥分配方案的平均光子数进行了优化,根据优化结果,利用GYS的实验参数分析了Lo等人提出的诱惑态量子密钥效率表达式,结果表明,误码系数修正后的表达式具有更高的密钥生成效率空间。

The quantum bit error rate（QBER） based on the weak coherent pulse′s quantum key distribution is analyzed.It is indicates that the coefficient of QBER is not a constant but is increased exponentially with the transmission distances.Based on the three experiments data,the function fitting has been done.We discover that these fitting functions have the same function form.Subsequently we use these functions to optimize the mean photon number for the BB84 quantum key distribution with decoy states.It is shown that the optimized mean photon number depends on the transmission distances.Based on these results and the GYS′s experimental parameters we compared the key generation rates proposed by Lo et al with the modified one.We find that the latter is superior to the former within a certain distance.