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±1% over one hour. A secure key rate of 1.398×10−5 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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BibTeX
@misc{mandil2026proofofprinciple,
title = {{Proof-of-principle long-distance Sagnac twin-field quantum key distribution network}},
author = {Reem Mandil and Yen-An Shih and Abhay Verma and Li Qian and Hoi-Kwong Lo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.04447},
eprint = {2609.04447},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04447},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Proof-of-principle long-distance Sagnac twin-field quantum key distribution network
AU - Reem Mandil
AU - Yen-An Shih
AU - Abhay Verma
AU - Li Qian
AU - Hoi-Kwong Lo
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2609.04447
UR - https://arxiv.org/abs/2609.04447
AB - 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±1% over one hour. A secure key rate of 1.398×10^−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.
ER -