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arXiv 1804.04879quant-ph
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大气对连续变量量子密钥分发的影响

Atmospheric effects on continuous-variable quantum key distribution

Shiyu Wang, Peng Huang, Tao Wang, Guihua Zeng

摘要:

与光纤连续变量量子密钥分发(CVQKD)相比,大气信道具有更广的地理覆盖范围和更灵活的传输方式,但大气信道存在许多不利的特性,如光束消光和各种湍流效应,会降低可实现的密钥速率。在这里,我们展示了这些因素如何影响CVQKD的性能,通过考虑我们新推导出的衰落信道的密钥速率公式,其中包括检测缺陷,从而形成CVQKD的传输模型。该模型可以帮助评估实验方案在实际应用中的可行性,我们发现边界层内水平链路的性能恶化主要是由透射率波动(包括光束漂移、展宽、变形和闪烁)引起的,而弱湍流下由脉冲展宽引起的透射率变化可以忽略不计。此外,我们还发现,当传输距离较长时,通信中断也会导致可感知的密钥速率降低,而由于到达时间波动引起的相位过量噪声需要新的补偿技术将其降低到可以忽略的水平。此外,它被发现,执行零差检测,使更长的传输距离,而外差允许更高的可实现的密钥速率在短距离。

英文摘要:

Compared to fiber continuous-variable quantum key distribution (CVQKD), atmospheric link offers the possibility of a broader geographical coverage and more flexible transmission.However, there are many negative features of the atmospheric channel that will reduce the achievable secret key rate, such as beam extinction and a variety of turbulence effects. Here we show how these factors affect performance of CVQKD, by considering our newly derived key rate formulas for fading channels,which involves detection imperfections, thus form a transmission model for CVQKD. This model can help evaluate the feasibility of experiment scheme in practical applications.We found that performance deterioration of horizontal link within the boundary layer is primarily caused by transmittance fluctuations (including beam wandering, broadening, deformation, and scintillation),while transmittance change due to pulse broadening under weak turbulence is negligible. Besides,we also found that communication interruptions can also cause a perceptible key rate reduction when the transmission distance is longer, while phase excess noise due to arrival time fluctuations requires new compensation techniques to reduce it to a negligible level. Furthermore, it is found that performing homodyne detection enables longer transmission distances, whereas heterodyne allows higher achievable key rate over short distances.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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