Point-to-multipoint network for continuous-variable quantum key distribution with passive-state preparation
Phys. Rev. Applied 25, 024012 – Published 4 February, 2026
DOI: https://doi.org/10.1103/8ydq-t8ht
Abstract
Passive-state-preparation continuous-variable quantum key distribution (CVQKD) leverages the inherent field fluctuations of thermal source for quantum state preparation, thereby eliminating the need for modulators and quantum random number generators. It not only contributes to the development of low-cost, miniaturized CVQKD systems, but also inherently closes all modulation-related security loopholes. Despite its advantages in facilitating scalable and cost-effective QKD networks, current passive-state-preparation CVQKD implementations remain confined to point-to-point configurations, constrained by low secret key rates and the lack of rigorous security proofs for multiuser protocols. In this work, we propose a point-to-multipoint (PTMP) CVQKD protocol with passive-state preparation, supported by a comprehensive security framework that enables simultaneous and independent key generation between the passive state source and all end users. Simulation results demonstrate that the protocol can support hundreds of users over transmission distances of tens of kilometers, making it highly suitable for metropolitan-area and access-network applications. The simplified source preparation, combined with concurrent key generation, lays the foundation for a high-performance and scalable CVQKD network, offering a practical and efficient pathway toward the realization of large-scale QKD infrastructures.
