Efficient and secure quantum secret sharing for eight users

Quantum secret sharing (QSS) has emerged as a promising avenue for storing secret with quantum-enhanced security. However, practical applications are hindered by the challenge for simultaneously implementing high-efficiency, high-security, and high-flexibility QSS with multiple users. Here we present an efficient, secure, and flexible QSS involving eight users with a continuous-variable eight-partite bound entanglement (BE) state, where only two nondegenerated optical parameter amplifiers are required. Such abilities are attributed to the generation of the eight-partite BE state with precise phase controlling systems and a large entanglement network, and fiber distribution with polarization-division multiplexing. In the QSS, a higher key rate can be demonstrated, when a secret is extracted through flexible combinations of more collaborative users. Our system may pave the way for the spatially separated multiuser quantum communications, while minimizing quantum hardware. Published by the American Physical Society 2024