Quantum key distribution overcoming practical correlated intensity fluctuations

Abstract Intensity correlations between neighbouring pulses open a prevalent yet often overlooked security loophole in decoy-state quantum key distribution (QKD). As a solution, we present and experimentally demonstrate an intensity-correlation-tolerant QKD protocol that mitigates the negative effec...

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Bibliographic Details
Main Authors: Jia-Xuan Li, Feng-Yu Lu, Ze-Hao Wang, Víctor Zapatero, Marcos Curty, Shuang Wang, Zhen-Qiang Yin, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:npj Quantum Information
Online Access:https://doi.org/10.1038/s41534-025-01059-0
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Summary:Abstract Intensity correlations between neighbouring pulses open a prevalent yet often overlooked security loophole in decoy-state quantum key distribution (QKD). As a solution, we present and experimentally demonstrate an intensity-correlation-tolerant QKD protocol that mitigates the negative effect that this phenomenon has on the secret key rate according to existing security analyses. Compared to previous approaches, our method significantly enhances the robustness against correlations, notably improving both the maximum transmission distances and the achievable secret key rates across different scenarios. By relaxing constraints on correlation parameters, our protocol enables practical devices to counter intensity correlations. We experimentally demonstrate this first practical solution that directly overcomes this security vulnerability, establish the feasibility and efficacy of our proposal, taking a major step towards loophole-free and high-performance QKD.
ISSN:2056-6387