Homodyne Detection Quadrature Phase Shift Keying Continuous-Variable Quantum Key Distribution with High Excess Noise Tolerance

TL;DR

This paper introduces a quadrature phase shift keying homodyne detection protocol for continuous-variable quantum key distribution, significantly improving excess noise tolerance and transmission distance, facilitating large-scale quantum communication networks.

Contribution

The paper proposes a novel homodyne detection protocol using quadrature phase shift keying that enhances noise tolerance and outperforms heterodyne detection under untrusted detector noise conditions.

Findings

Achieves high excess noise tolerance in CV-QKD.

Homodyne detection outperforms heterodyne detection under certain noise scenarios.

Enables secure key distribution over nearly intercity distances.

Abstract

Discrete-modulated continuous-variable quantum key distribution with homodyne detection is widely recognized for its ease of implementation, efficiency with respect to error correction, and its compatibility with modern optical communication devices. However, recent studies report that the application of homodyne detection obtains poor tolerance to excess noise and insufficient transmission distance, hence seriously restricting the large-scale deployment of quantum secure communication networks. In this paper, we propose a homodyne detection protocol using the quadrature phase shift keying technique. By limiting information leakage, our proposed protocol enhances excess noise tolerance to a high level. Furthermore, we demonstrate that homodyne detection performs better than heterodyne detection in quaternary-modulated continuous-variable quantum key distribution under the untrusted detector noise scenario. The security is analyzed using the tight numerical method against collective attacks in the asymptotic regime. Our results imply that the current protocol is able to distribute keys in nearly intercity area and thus paves the way for constructing low-cost quantum secure communication networks.