Enhanced continuous-variable quantum key distribution protocol via adaptive signal processing

Fuente: arXiv
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Main Authors: Erkilic, Ozlem, Shajilal, Biveen, Conlon, Lorcan O., Walsh, Angus, Das, Aritra, Kish, Sebastian, Symul, Thomas, Lam, Ping Koy, Assad, Syed M., Zhao, Jie
Format: Preprint
Published: 2025
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author Erkilic, Ozlem
Shajilal, Biveen
Conlon, Lorcan O.
Walsh, Angus
Das, Aritra
Kish, Sebastian
Symul, Thomas
Lam, Ping Koy
Assad, Syed M.
Zhao, Jie
author_facet Erkilic, Ozlem
Shajilal, Biveen
Conlon, Lorcan O.
Walsh, Angus
Das, Aritra
Kish, Sebastian
Symul, Thomas
Lam, Ping Koy
Assad, Syed M.
Zhao, Jie
contents Quantum key distribution (QKD) provides a promising approach to secure communications, with continuous-variable QKD (CV-QKD) offering compatibility with existing telecommunication infrastructure. Despite this advantage, CV-QKD is limited by challenges such as losses in terrestrial fibres and atmospheric scintillation in free-space channels. We introduce a QKD protocol that surpasses the optimal Gaussian modulated CV-QKD (GG02) protocol by utilising probabilistic filters without known physical representation. Our approach employs a Gaussian filter at Alice's station and a non-Gaussian notch-like filter at Bob's station. Alice's filter optimises modulation variance to achieve key rates near the optimal GG02 performance, while Bob's filter adapts the effective channel conditions, which can result in higher key rates than the optimal GG02 protocol. Our security analysis avoids Gaussian extremality, accurately bounding Eve's information. The protocol dynamically optimises the secret-key rate for rapidly changing channels, such as terrestrial links and satellite-to-ground communications, and can extract keys in regions deemed non-secure by parameter estimation. Implemented at software level, our protocol requires no hardware modifications and can be integrated into existing QKD systems. Experimental results show a threefold increase in key rates over the optimal GG02 protocol, while simulations for Low Earth Orbit satellite quantum communications indicate a 400-fold increase compared to the non-optimised counterpart.
format Preprint
id arxiv_https___arxiv_org_abs_2507_18049
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Enhanced continuous-variable quantum key distribution protocol via adaptive signal processing
Erkilic, Ozlem
Shajilal, Biveen
Conlon, Lorcan O.
Walsh, Angus
Das, Aritra
Kish, Sebastian
Symul, Thomas
Lam, Ping Koy
Assad, Syed M.
Zhao, Jie
Quantum Physics
Quantum key distribution (QKD) provides a promising approach to secure communications, with continuous-variable QKD (CV-QKD) offering compatibility with existing telecommunication infrastructure. Despite this advantage, CV-QKD is limited by challenges such as losses in terrestrial fibres and atmospheric scintillation in free-space channels. We introduce a QKD protocol that surpasses the optimal Gaussian modulated CV-QKD (GG02) protocol by utilising probabilistic filters without known physical representation. Our approach employs a Gaussian filter at Alice's station and a non-Gaussian notch-like filter at Bob's station. Alice's filter optimises modulation variance to achieve key rates near the optimal GG02 performance, while Bob's filter adapts the effective channel conditions, which can result in higher key rates than the optimal GG02 protocol. Our security analysis avoids Gaussian extremality, accurately bounding Eve's information. The protocol dynamically optimises the secret-key rate for rapidly changing channels, such as terrestrial links and satellite-to-ground communications, and can extract keys in regions deemed non-secure by parameter estimation. Implemented at software level, our protocol requires no hardware modifications and can be integrated into existing QKD systems. Experimental results show a threefold increase in key rates over the optimal GG02 protocol, while simulations for Low Earth Orbit satellite quantum communications indicate a 400-fold increase compared to the non-optimised counterpart.
title Enhanced continuous-variable quantum key distribution protocol via adaptive signal processing
topic Quantum Physics
url https://arxiv.org/abs/2507.18049