Hang Liu

Among all existing quantum key distribution (QKD) protocols, the round-robin-differential-phase-shift (RRDPS) protocol is one of the unique protocols. Because it can be running without monitoring signal disturbance, which improves its tolerance of error rate and does well in the finite-key scenario. Considering that a tight finite-key analysis with a practical phase-randomized source is still missing, we propose an improved security proof of RRDPS against the most general coherent attack based on the entropic uncertainty relation. We also introduce Azuma’s inequality into our proof, which can tackle finite-key effects. The results indicate experimentally acceptable numbers of pulses are sufficient to approach the asymptotic bound closely. This method may be the optimal one in the finite-key analysis for the RRDPS protocol.