Discrete-phase-randomized mode-pairing quantum key distribution

Fuente: arXiv
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Auteurs principaux: Xu, Yuewei, Lu, Zeyang, Li, Chan, Long, Jian, Cao, Zhu
Format: Preprint
Publié: 2026
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author Xu, Yuewei
Lu, Zeyang
Li, Chan
Long, Jian
Cao, Zhu
author_facet Xu, Yuewei
Lu, Zeyang
Li, Chan
Long, Jian
Cao, Zhu
contents Mode-pairing quantum key distribution (MP-QKD) protocol achieves performance beyond the repeaterless rate-transmittance bound and exhibits excellent practicality by avoiding the requirement for difficult global phase locking. However, the source side of MP-QKD still relies on the assumption of continuous phase randomization, an experimentally infeasible requirement in practice. Therefore, the practical security of the protocol cannot be fully guaranteed. In this work, we propose a discrete-phase-randomized mode-pairing quantum key distribution (DPR-MP-QKD) protocol and analyze the basis-dependence of the source side. Then, we introduce a concrete discrete version of the decoy state method that ensures the security of the DPR-MP-QKD protocol. Finally, simulation results indicate that as the number of discrete phases increases, the key rate performance of DPR-MP-QKD progressively approaches that of the continuous case, with convergence achieved at approximately 14 discrete phases. Moreover, our approach drastically lowers the demand for randomness. While conventional continuous phase randomization demands an unlimited supply of random bits, we show that merely a few bits (e.g., 4) are adequate.
format Preprint
id arxiv_https___arxiv_org_abs_2605_14484
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Discrete-phase-randomized mode-pairing quantum key distribution
Xu, Yuewei
Lu, Zeyang
Li, Chan
Long, Jian
Cao, Zhu
Quantum Physics
Mode-pairing quantum key distribution (MP-QKD) protocol achieves performance beyond the repeaterless rate-transmittance bound and exhibits excellent practicality by avoiding the requirement for difficult global phase locking. However, the source side of MP-QKD still relies on the assumption of continuous phase randomization, an experimentally infeasible requirement in practice. Therefore, the practical security of the protocol cannot be fully guaranteed. In this work, we propose a discrete-phase-randomized mode-pairing quantum key distribution (DPR-MP-QKD) protocol and analyze the basis-dependence of the source side. Then, we introduce a concrete discrete version of the decoy state method that ensures the security of the DPR-MP-QKD protocol. Finally, simulation results indicate that as the number of discrete phases increases, the key rate performance of DPR-MP-QKD progressively approaches that of the continuous case, with convergence achieved at approximately 14 discrete phases. Moreover, our approach drastically lowers the demand for randomness. While conventional continuous phase randomization demands an unlimited supply of random bits, we show that merely a few bits (e.g., 4) are adequate.
title Discrete-phase-randomized mode-pairing quantum key distribution
topic Quantum Physics
url https://arxiv.org/abs/2605.14484