Tight finite-key analysis for passive decoy-state quantum key distribution under general attacks

TL;DR

This paper presents a tight finite-key analysis for passive decoy-state quantum key distribution using SPDCSs, demonstrating near-optimal secure distances and performance comparable to active protocols under finite-size effects.

Contribution

It introduces a concise formula for the key rate in passive decoy-state QKD with SPDCSs, combining security bounds with finite-key analysis.

Findings

Secure distance up to 182 km with 10^10 sifted data

Passive decoy-state QKD performs comparably to active protocols under finite-size effects

A new tight finite-key analysis method for passive decoy-state QKD

Abstract

For quantum key distribution (QKD) using spontaneous parametric-down-conversion sources (SPDCSs), the passive decoy-state protocol has been proved to be efficiently close to the theoretical limit of an infinite decoy-state protocol. In this paper, we apply a tight finite-key analysis for the passive decoy-state QKD using SPDCSs. Combining the security bound based on the uncertainty principle with the passive decoy-state protocol, a concise and stringent formula for calculating the key generation rate for QKD using SPDCSs is presented. The simulation shows that the secure distance under our formula can reach up to 182 km when the number of sifted data is $10^{10}$. Our results also indicate that, under the same deviation of statistical fluctuation due to finite-size effects, the passive decoy-state QKD with SPDCSs can perform as well as the active decoy-state QKD with a weak coherent source.