Unconditional security of entanglement-based continuous-variable quantum secret sharing

TL;DR

This paper proves the unconditional security of continuous-variable entanglement-based quantum secret sharing schemes, demonstrating their feasibility with practical Gaussian states and homodyne measurements for multiple parties.

Contribution

It provides the first unconditional security proof for such schemes using a one-sided device-independent approach, applicable to an arbitrary number of players.

Findings

Security holds in the asymptotic key limit.

Scheme can be implemented with Gaussian states and homodyne detection.

No need for ideal single-photon sources or quantum memories.

Abstract

The need for secrecy and security is essential in communication. Secret sharing is a conventional protocol to distribute a secret message to a group of parties, who cannot access it individually but need to cooperate in order to decode it. While several variants of this protocol have been investigated, including realizations using quantum systems, the security of quantum secret sharing schemes still remains unproven almost two decades after their original conception. Here we establish an unconditional security proof for continuous variable entanglement-based quantum secret sharing schemes, in the limit of asymptotic keys and for an arbitrary number of players. We tackle the problem by resorting to the recently developed one-sided device-independent approach to quantum key distribution. We demonstrate theoretically the feasibility of our scheme, which can be implemented by Gaussian states and homodyne measurements, with no need for ideal single-photon sources or quantum memories. Our results contribute to validating quantum secret sharing as a viable primitive for quantum technologies.