A modified practical homodyne detector model for continuous-variable quantum key distribution: detailed security analysis and improvement by the phase-sensitive amplifier

TL;DR

This paper introduces a modified practical homodyne detector model for continuous-variable quantum key distribution that separately models detector imperfections and employs a phase-sensitive amplifier to enhance performance and security.

Contribution

The paper proposes a new homodyne detector model that isolates imperfections and demonstrates how a phase-sensitive amplifier can fully compensate limited detection efficiency.

Findings

The phase-sensitive amplifier improves detector performance.

Full compensation of limited detection efficiency at infinite gain.

Enhanced security analysis of the modified model.

Abstract

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 is further applied to compensate the imperfections of the practical homodyne detector. The feasibility of the modified practical homodyne detector model with the phase-sensitive amplifier is proved and the security analysis is provided in detail. Simulation results reveal that the phase-sensitive amplifier 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.