Receiver-device-independent quantum secure direct communication

Abstract

Quantum secure direct communication (QSDC) enables the sender to directly transmit secure messages to the receiver via a quantum channel without the need for keys. Device-independent (DI) and measurement-device-independent (MDI) QSDC protocols theoretically enhance the practical security of QSDC. However, DI QSDC requires extremely high global detection efficiency and has a limited secure communication distance. Both DI and MDI QSDC protocols depend on high-quality entanglement. Current entanglement sources, which generate entangled photon pairs with low efficiency, significantly reduce their practical communication capabilities. In this paper, we propose a single-photon-based receiver-device-independent (RDI) QSDC protocol. This protocol relies solely on the practical single-photon source, which is nearly on-demand with current technology, and treats all receiving devices on both ends of the communication as “black boxes”. The security of the message is ensured only through the observed statistics. We also develop a numerical method to simulate the protocol’s performance under practical noisy communication conditions. The RDI QSDC protocol provides the same security level as MDI QSDC. Compared to DI and MDI QSDC, RDI QSDC has several advantages. First, it uses single-photon sources and single-photon measurements, which allow it to achieve practical communication efficiency approximately 3415 times greater than that of DI QSDC, while being easier to implement. The entire protocol is feasible with current technology. Second, it offers higher robustness to photon loss and better noise tolerance than DI QSDC, enabling a secure communication distance approximately 26 times greater than that of DI QSDC. Based on these advantages, the RDI QSDC protocol presents a promising approach for achieving highly secure and efficient QSDC in the near future.