Thermal state continuous-variable quantum key distribution via fast fading channel

• Published in: Physica scripta Vol. 100; no. 7; pp. 75119 - 75131
• Main Authors: Tian, Yue, Zhou, Jian, Zhao, Runbo, Shi, Ronghua, Shi, Jinjing, Feng, Yanyan
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.07.2025
• Subjects: CV-QKD; fast fading channel; heterodyne; reconciliation; thermal state
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/1402-4896/ade6db

This study examines the implementation of continuous-variable quantum key distribution (CV-QKD) using thermal states via fast fading channel. In such channel, communication occurs in free space under adverse conditions such as atmospheric turbulence, causing the channel transmittance to vary according to a specific mathematical probability. In worst-case scenarios, an eavesdropper could fully control the channel, leaving communicators to make pessimistic assumptions about channel conditions. The security of this system is analyzed and evaluated using homodyne and heterodyne detection methods under reverse reconciliation. The results indicate that even with full eavesdropper control, employing noise sources in CV-QKD ensures high key rates and protocol security. Furthermore, it has been demonstrated that the introduction of preparation noise in heterodyne detection is more effective than homodyne detection under fast fading channel conditions.