High-performance continuous-variable quantum secret sharing using a state-discrimination detector

Abstract Continuous-variable quantum secret sharing (CVQSS) is a promising approach to ensuring multi-party information security. While CVQSS offers practical ease of implementation, its present performance remains limited. In this paper, we propose a novel CVQSS protocol integrated with a state-discrimination detector (SDD), dubbed SDD-CVQSS. In particular, we first develop the detailed procedure of SDD-CVQSS, which replaces the traditional coherent detector with an SDD and eliminates the long-standing necessary step of establishing multiple point-to-point quantum key distribution links between all users and the dealer. We then elaborate on the principle of the specifically designed SDD, which can efficiently discriminate interfered states with a much lower error probability. Finally, we construct a security model for SDD-CVQSS and derive its security bound against both eavesdroppers and dishonest users. Numerical simulations show that SDD-CVQSS outperforms conventional CVQSS in terms of both maximum transmission distance and secret key rate, and its performance is even superior to the PLOB bound. Additionally, we find that the performance degradation of SDD-CVQSS in long-distance transmission scenarios can be effectively compensated for using a post-selection scheme, providing a feasible way to achieve high-performance CVQSS.