Four-state reference-frame-independent quantum key distribution with non-qubit source flaws

The discrepancy between theory and experiment severely limits the development of quantum key distribution (QKD). Reference-frame-independent (RFI) protocols have been proposed to avoid alignment of the reference frame with the assumption of qubit systems. However, Trojan horse attacks and high-dimensional information leakage caused by equipment loopholes inevitably result in an imperfect non-qubit emitted signal. In this paper, we analyze the security of the RFI-QKD protocol with non-qubit source flaws based on a generalizing loss-tolerant method. The simulation results show that it is feasible to employ non-qubit flaw sources without compromising the security of the QKD system. Moreover, it only requires the preparation of four quantum states, which reduces the complexity of the experiment. (C) 2022 Optica Publishing Group