Practical Methods for Distance-Adaptive Continuous-Variable Quantum Key Distribution

Fuente: arXiv
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Auteurs principaux: Berl, Jonas, Akin, Utku, Cil, Erdem Eray, Schmalen, Laurent, Fehenberger, Tobias
Format: Preprint
Publié: 2026
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author Berl, Jonas
Akin, Utku
Cil, Erdem Eray
Schmalen, Laurent
Fehenberger, Tobias
author_facet Berl, Jonas
Akin, Utku
Cil, Erdem Eray
Schmalen, Laurent
Fehenberger, Tobias
contents Continuous-variable quantum key distribution (CV-QKD) is a promising quantum-safe alternative to classical asymmetric cryptography that enables two authenticated parties to establish a shared secret over a potentially eavesdropped quantum channel. A key step in CV-QKD post-processing is information reconciliation, which leverages forward error correction (FEC) techniques to extract identical bit strings from noisy correlated data. In this work, we analyze the strict limitations on operating distance that are imposed by constant-rate FEC, severely limiting the practicability of CV-QKD systems in deployed optical networks. To overcome the distance limitations, we evaluate three strategies: (i) tuning modulation variance, (ii) adding controlled amounts of trusted detector loss, and (iii) the use of rate-adaptive FEC. All approaches are validated experimentally, compared in terms of performance, and we discuss implementation aspects. Our results show that while methods (i) and (ii) extend the operational distance of constant-rate FEC without the need for additional hardware components, they incur a significant penalty in secret key rate (SKR). In contrast, rate-adaptive FEC enables CV-QKD operation with performance close to the asymptotic SKR over a wide range of distances, provided that the reconciliation efficiency is chosen appropriately.
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id arxiv_https___arxiv_org_abs_2603_10480
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Practical Methods for Distance-Adaptive Continuous-Variable Quantum Key Distribution
Berl, Jonas
Akin, Utku
Cil, Erdem Eray
Schmalen, Laurent
Fehenberger, Tobias
Quantum Physics
Continuous-variable quantum key distribution (CV-QKD) is a promising quantum-safe alternative to classical asymmetric cryptography that enables two authenticated parties to establish a shared secret over a potentially eavesdropped quantum channel. A key step in CV-QKD post-processing is information reconciliation, which leverages forward error correction (FEC) techniques to extract identical bit strings from noisy correlated data. In this work, we analyze the strict limitations on operating distance that are imposed by constant-rate FEC, severely limiting the practicability of CV-QKD systems in deployed optical networks. To overcome the distance limitations, we evaluate three strategies: (i) tuning modulation variance, (ii) adding controlled amounts of trusted detector loss, and (iii) the use of rate-adaptive FEC. All approaches are validated experimentally, compared in terms of performance, and we discuss implementation aspects. Our results show that while methods (i) and (ii) extend the operational distance of constant-rate FEC without the need for additional hardware components, they incur a significant penalty in secret key rate (SKR). In contrast, rate-adaptive FEC enables CV-QKD operation with performance close to the asymptotic SKR over a wide range of distances, provided that the reconciliation efficiency is chosen appropriately.
title Practical Methods for Distance-Adaptive Continuous-Variable Quantum Key Distribution
topic Quantum Physics
url https://arxiv.org/abs/2603.10480