Jian-Rong Zhu, Chun-Mei Zhang, Rong Wang
The reference-frame-independent measurement-device-independent quantum key distribution (RFI-MDI-QKD) protocol is immune to both the slow drift of the reference frame and the potential attacks aimed at the measurement device. However, its reference-frame-independent behavior in terms of performance relies on the assumption that the key-generation basis is well aligned, which may not always be satisfied in practice. In this work, to address this limitation in RFI-MDI-QKD, we propose a fully RFI-MDI-QKD (FRFI-MDI-QKD) protocol by harnessing the quantum discord resource, and prove its security against collective attacks in the asymptotic case. With a 3 × 3 matrix whose singular values are independent of the reference frame, the information obtained by the eavesdropper in FRFI-MDI-QKD is completely irrelevant to the reference frame. Simulation results show that, in the case of a misaligned key-generation basis, FRFI-MDI-QKD can yield more positive keys compared with previous RFI-MDI-QKD; in the case of a well-calibrated key-generation basis, the key rate performance of FRFI-MDI-QKD can be reduced to that of previous RFI-MDI-QKD.