Measurement-Device-Independent Continuous-Variable Quantum Secret Sharing

Abstract

Although continuous-variable quantum secret sharing (CVQSS) is theoretically proven to be secure, it may still be subject to various practical attacks due to the imperfections of devices. In this study, measurement-device-independent CVQSS (MDI-CVQSS) is proposed in which measurement is no longer the duty for the dealer but is performed by an untrusted party Charlie, so that all detector side-channel attacks can be eliminated, greatly enhancing the practical security of CVQSS system. The security bound is derived for the proposed MDI-CVQSS, and its numerical simulation shows that MDI-CVQSS outperforms conventional CVQSS in terms of both secret key rate and maximal number of users. It is found that MDI-CVQSS possesses several unique properties, such as local stability of the secret key rate, low total excess noise and high utilization rate of raw data, which indicate that MDI-CVQSS has the potential for efficiently building a large-scale quantum communication network. Moreover, it is also suggested three variations of MDI-CVQSS to satisfy the requirements of different multi-point quantum communication scenarios.