Practical decoy-state round-robin differential-phaseshift quantum key distribution

TL;DR

This paper evaluates and enhances the practical implementation of the RRDPS quantum key distribution protocol using decoy states, demonstrating its effectiveness over long distances with realistic photon sources.

Contribution

It introduces a finite decoy-state method for RRDPS, improving practical security and performance with realistic photon sources like WCPs and HSPS.

Findings

Secret keys can be distributed over 128 km with three-intensity decoy states.

The finite decoy-state method performs close to the ideal infinite case.

Practical implementation with WCPs is feasible for long-distance QKD.

Abstract

To overcome the signal disturbance from the transmission process, recently, a new type of protocol named round-robin differential-phase-shift(RRDPS) quantum key distribution[Nature 509, 475(2014)] is proposed. It can estimate how much information has leaked to eavesdropper without monitoring bit error rates. In this paper, we compare the performance of RRDPS using different sources without and with decoy-state method, such as weak coherent pulses(WCPs) and heralded single photon source(HSPS). For practical implementations, we propose finite decoy-state method for RRDPS, the performance of which is close to the infinite one. Taking WCPs as an example, the three-intensity decoystate protocol can distribute secret keys over a distance of 128 km when the length of pulses packet is 32, which confirms the great practical interest of our method.