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

Abstract

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.