Quantum key distribution is a cornerstone of quantum technology, offering information-theoretical secure keys for remote parties. With many quantum communication networks established globally, the mode-pairing protocol stands out for its efficacy over inter-city distances using simple setups, emerging as a promising solution. In this study, we employ the mode-pairing scheme into existing inter-city fiber links, conducting field tests across distances ranging from tens to about a hundred kilometers. Our system achieves a key rate of 1.217 kbit/s in a 195.85 km symmetric link and 3.089 kbit/s in a 127.92 km asymmetric link without global phase locking. The results demonstrate that the mode-pairing protocol can achieve key rates comparable to those of a single quantum link between two trusted nodes on the Beijing-Shanghai backbone line, effectively reducing the need for half of the trusted nodes. These field tests confirm the mode-pairing scheme's adaptability, efficiency, and practicality, positioning it as a highly suitable protocol for quantum networks.
@article{arxiv.2403.09339,
title = {Field test of mode-pairing quantum key distribution},
author = {Hao-Tao Zhu and Yizhi Huang and Wen-Xin Pan and Chao-Wu Zhou and Jianjun Tang and Hong He and Ming Cheng and Xiandu Jin and Mi Zou and Shibiao Tang and Xiongfeng Ma and Teng-Yun Chen and Jian-Wei Pan},
journal= {arXiv preprint arXiv:2403.09339},
year = {2024}
}