Device-Independent Quantum Secure Direct Communication with Single-Photon

Quantum secure direct communication (QSDC) can directly transmit secrete messages through a quantum channel. Device-independent (DI) QSDC can guarantee the communication security relying only on the observation of the Bell-inequality violation, but not on any detailed description or trust of the inner workings of users' devices. In the paper, we propose a DI-QSDC protocol with practical highly efficient single-photon sources. The communication parties construct the entanglement channel from single photons by adopting the heralded architecture, which makes the message-leakage rate independent of the photon-transmission loss. The secure communication distance and the practical communication efficiency of the current DI-QSDC protocol are about 6 times and 600 times of those in the original DI-QSDC protocol. Combining with the entanglement purification, the parties can construct the nearly perfect entanglement channel and completely eliminate the message leakage. This DI-QSDC protocol may have useful applications in the future quantum communication field.