paper

Approaching the Key Rate Limit in Continuous-Variable Quantum Key Distribution Network

arXiv:2507.04462 · doi:10.1103/3c11-1yp3

Abstract

A quantum key distribution network enables pairs of users to generate independent secret keys by leveraging the principles of quantum physics. For end-to-end secure communication, a user pair's secret key must remain secure against any third parties, including both external eavesdroppers and other network users. However, isolating a given user pair from the remaining users while maintaining a high key rate is challenging when all users are intrinsically coupled and correlated, particularly in continuous-variable networks. This results in either a low key rate, or incomplete end-to-end security. Here, we introduce a multi-user security framework, offering a general and comprehensive end-to-end key rate formula, against the collaboration of the other network users and eavesdropper. Building on this framework, we propose a multi-user protocol that achieves the theoretical upper limit in all practical deployments within a 100 km range. Applied to a three-node network, it achieves an Mbps-level per-user key rate and an overall network key rate reaching 90\% of the upper limit. The proposed solution supports scalable implementations using telecom-compatible components, while the method for obtaining the accessible information in the network is broadly applicable and can be extended to various multipartite quantum information systems.

17 pages, 20 figures

References in corpus (24)