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

• URL: http://arxiv.org/abs/2609.04447v1
• Date: Thu, 03 Sep 2026 20:10:07 GMT
• Title: Proof-of-principle long-distance Sagnac twin-field quantum key distribution network
• Abstract summary: We experimentally demonstrate a proof-of-principle three-user-pair Sagnac TFQKD network spanning 127-km using single-photon avalanche detectors.<n>A secure key rate of $1.398times10-5$ bits per pulse is achieved over an asymmetric communication channel with 102-km fiber and 45-dB overall loss.
• Score: 0.48745947329256945
• License: http://creativecommons.org/licenses/by/4.0/
• 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.

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