Secure quantum key distribution against correlated leakage source

TL;DR

This paper introduces a new security analysis framework for quantum key distribution that accounts for correlated source leakage, enabling finite-key analysis and improving security against practical imperfections.

Contribution

It develops a novel framework for analyzing QKD security under correlations, extending finite-key analysis and proposing a protocol secure against correlated leakage sources.

Findings

Framework enables finite-key analysis under correlations

Proposed protocol shows superior tolerance to imperfections

Framework applicable to various QKD protocols

Abstract

Quantum key distribution (QKD) provides information theoretic security based on quantum mechanics, however, its practical deployment is challenged by imperfections of source devices. Among various source loopholes, correlations between transmitted pulses pose a significant yet underexplored security risk, potentially compromising QKD's theoretical guarantees. In this work, we propose a security analysis framework for QKD under correlations, enabling finite-key analysis for the first time by extending and rearranging QKD rounds and leveraging the generalized chain rule. Based on this framework, and inspired by the idea of side-channel-secure QKD, we develop a secure QKD against correlated leakage source only need the characterization of correlation range and the lower bound on the vacuum component of the prepared states. Additionally, our framework can be extended to other QKD protocols, offering a general approach to consider correlation induced security vulnerabilities. The simulation results demonstrate the effectiveness of our protocol and its significantly superior tolerance to imperfect parameters compared to existing protocols. This work provides a crucial step toward closing security loopholes in QKD, enhancing its practicality, and ensuring long-distance,high-performance secure communication under real-world constraints.