Performance Improvement of Continuous-Variable Quantum Secret Sharing via Heralded Hybrid Linear Amplifier

Continuous-variable quantum secret sharing (CVQSS) enables multiple players (at least three) to share a secret key using weak coherent states, which are easy to prepare and resilient to losses. Despite these advantages, CVQSS encounters challenges such as low secret key rates and limited maximum transmission distances, particularly when dealing with a large number of players. This paper proposes a novel scheme to enhance CVQSS performance by incorporating a heralded hybrid linear amplifier (HHLA). The HHLA combines a deterministic linear amplifier (DLA) and a noiseless linear amplifier (NLA), effectively functioning as an improved noiseless linear amplifier with a higher probability of successful amplification. Additionally, the HHLA offers tunable gain settings, including a high-gain mode and a high noise-reduction mode, to optimize noise penalties form measurements and enhance CVQSS performance. Numerical simulations demonstrate that even with 100 connected nodes, the HHLA-based CVQSS scheme achieves a maximum transmission distance exceeding 60 km.