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Continuous-variable quantum key distribution under strong channel polarization disturbance
Physical Review A ( IF 2.9 ) Pub Date : 2020-09-25 , DOI: 10.1103/physreva.102.032625
Wenyuan Liu , Yanxia Cao , Xuyang Wang , Yongmin Li

In a commercial fiber-based quantum key distribution (QKD) system, the state of polarization (SOP) of the optical fields is inevitably disturbed by random birefringence of the standard single-mode fiber due to an external complex environment. We analyze theoretically the effect of SOP fluctuations on the continuous-variable (CV) QKD system and experimentally verify its validity. To overcome the influence of the polarization variations, a self-adaptive gradient algorithm is proposed to achieve high-speed polarization controlling under pulsed light with field programmable gate array hardware. For single random polarization scrambling, the polarization extinction ratio achieved is over 30 dB and the average time of polarization control is 827 μs. In order to eliminate further the effect of the occasional failures of polarization control, we properly filter the raw keys in terms of the relative phase fluctuations between the signal and the local oscillator. By combining this approach with the high-speed polarization control, we demonstrate a CV QKD under a continuous polarization scrambling of 314 rad/s. Our results provide useful references for practical application of fiber-based CV QKD in a field environment.

中文翻译:

强信道极化扰动下的连续变量量子密钥分布

在商用的基于光纤的量子密钥分配(QKD)系统中,由于外部复杂环境,标准单模光纤的随机双折射不可避免地会干扰光场的偏振状态(SOP)。我们从理论上分析了SOP波动对连续变量(CV)QKD系统的影响,并通过实验验证了其有效性。为了克服偏振变化的影响,提出了一种自适应梯度算法,利用现场可编程门阵列硬件实现了脉冲光下的高速偏振控制。对于单次随机极化扰码,实现的极化消光比超过30 dB,平均极化控制时间为827μs。为了进一步消除偶尔出现的偏振控制失败的影响,我们根据信号和本地振荡器之间的相对相位波动对原始密钥进行了适当的滤波。通过将此方法与高速极化控制相结合,我们演示了在314 rad / s的连续极化加扰下的CV QKD。我们的结果为在现场环境中基于光纤的CV QKD的实际应用提供了有用的参考。
更新日期:2020-09-25
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