Proof-of-principle long-distance Sagnac twin-field quantum key distribution network

Abstract:Twin-field (TF) quantum key distribution (QKD) offers a promising approach to long-distance QKD networks due to its superior performance over large channel losses. Due to specialized hardware requirements, nearly all long-distance TFQKD demonstrations have only two users exchanging keys, rather than a network with three or more users. In this work, we experimentally demonstrate a proof-of-principle three-user-pair Sagnac TFQKD network spanning 127-km using single-photon avalanche detectors without any active phase stabilization or postcompensation. We implement efficient procedures for maintaining polarization stability and circumventing Rayleigh backscattering noise to achieve a stable Sagnac interference visibility of $93\pm1$% over one hour. A secure key rate of $1.398\times10^{-5}$ bits per pulse is achieved over an asymmetric communication channel with 102-km fiber and 45-dB overall loss. To our knowledge, this is the first TFQKD network without active phase stabilization or postcompensation achieved over long fibers. Our results represent a highly practical and cost-effective approach to long-distance QKD networks.

Quantum Physics (quant-ph); Applied Physics (physics.app-ph); Optics (physics.optics)

arXiv:2609.04447 [quant-ph]

(or arXiv:2609.04447v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2609.04447 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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