Long-distance device-independent quantum secret sharing with noiseless linear amplification and entanglement purification

Quantum secret sharing (QSS) is a fundamental primitive of quantum network that enables multiple parties to securely share secret keys. Device-independent (DI) QSS offers the highest security by removing the assumptions on all experimental devices. However, the photon transmission loss and quantum state decoherence largely limit DI QSS’s secure photon transmission distance and experimental demonstration. For resisting above two obstacles, in this work, we propose a new DI QSS protocol that integrates two passive improvement strategies, the noiseless linear amplification (NLA) and entanglement purification. These passive strategies can completely eliminate the influence from photon transmission loss and improve entanglement distribution quality. In this way, DI QSS’s secure photon transmission distance can be extended to infinity in theory and its noise robustness can be largely enhanced (The threshold of the initial fidelity can be reduced from 85.71% to 65.75%). The NLA and EPP are based on linear optical elements, ensuring their experimental feasibility. We also introduce active improvement strategies in this DI QSS protocol, which can reduce its requirements on local experimental devices and further increase its noise robustness. The fidelity threshold can be further reduced to 59.73%. Our DI QSS protocol provides a possible solution for constructing DI multi-party long-distance quantum network.