The practical homodyne detector model of continuous-variable quantum key distribution models the inherent imperfections of the practical homodyne detector, namely the limited detection efficiency and the electronic noise, into trusted loss. However, the conventional practical homodyne detector model is valid only when both the imperfections of the practical homodyne detector are calibrated. In this paper, we show a modified practical homodyne detector model that can model the imperfections separately. The phase-sensitive amplifier (PSA) is further applied to compensate the imperfections of the practical homodyne detector. The feasibility of the modified practical homodyne detector model with the PSA is proved and the security analysis is provided in detail. Simulation results reveal that the PSA can be used to improve the performance of the modified practical homodyne detector model, and when the gain is infinitely high, the limited detection efficiency can be fully compensated.

连续可变量子密钥分布的实用零差检测器模型将实用零差检测器的固有缺陷（即有限的检测效率和电子噪声）建模为可信任的损失。然而，常规的实际零差检测器模型仅在校正了实际零差检测器的两个缺陷时才有效。在本文中，我们展示了一种经过修改的实用零差探测器模型，该模型可以分别对缺陷进行建模。相敏放大器（PSA）还用于补偿实际零差检测器的缺陷。证明了用PSA改进的实用零差探测器模型的可行性，并提供了安全性分析。