The value of residual phase noise, after phase compensation, is one of the key limitations of performance improvement for continuous-variable quantum key distribution using a local local oscillator (LLO CV-QKD) system, since it is the major excess noise. However, due to the nonideality of the realistic devices implemented in practice, for example, imperfect lasers, detectors, and unbalanced interferometers, the value of residual phase noise in the current system is still relatively large. Here, we develop a phase noise model to improve the phase noise tolerance of the LLO CV-QKD schemes. In our model, part of the phase-reference measurement noise associated with detection efficiency and electronic noise of Bob's detector as well as a real-time monitored phase-reference intensity at Bob's side is considered trusted because it can be locally calibrated by Bob. We show that using our phase noise model can significantly improve the secure key rate and transmission distance of the LLO CV-QKD system. We further conduct an experiment to substantiate the superiority of the phase noise model. Based on experimental data of a LLO CV-QKD system in the 25-km optical fiber channel, we demonstrate that the secure key rate under our phase noise model is approximately 40% higher than that under the conventional phase noise model.

中文翻译：

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使用本地本地振荡器的连续可变量子密钥分配的相位噪声模型

相位补偿后的残余相位噪声值是使用本地本地振荡器 (LLO CV-QKD) 系统的连续可变量子密钥分配性能改进的关键限制之一，因为它是主要的过量噪声。然而，由于实际实现的现实设备的不理想性，例如不完善的激光器、探测器和不平衡干涉仪，当前系统中残余相位噪声的值仍然较大。在这里，我们开发了一个相位噪声模型来提高 LLO CV-QKD 方案的相位噪声容限。在我们的模型中，部分相位参考测量噪声与 Bob 检测器的检测效率和电子噪声以及 Bob' 处实时监测的相位参考强度相关 s 端被认为是可信的，因为它可以由 Bob 本地校准。我们表明，使用我们的相位噪声模型可以显着提高 LLO CV-QKD 系统的安全密钥率和传输距离。我们进一步进行了实验以证实相位噪声模型的优越性。基于 25 公里光纤通道中 LLO CV-QKD 系统的实验数据，我们证明我们的相位噪声模型下的安全密钥率比传统相位噪声模型下的安全密钥率高约 40%。