Reference-frame-independent quantum key distribution with modified coherent states

Reference-frame-independent quantum key distribution (RFI-QKD) can generate secret keys in the presence of unknown and slowly drifting reference frames. Due to the unavoidable multiphoton events in practical weak coherent states (WCS), the decoy-state method is adopted to combat the potential photon-number-splitting attacks. In this paper, we adopt modified coherent states (MCS), which can eliminate certain multiphoton events based on quantum interference, to implement decoy-state RFI-QKD. Simulation results show that, compared with WCS, MCS can improve the secret key rate and transmission distance in RFI-QKD.