Year: 2025
Type: preprint
Abstract: Twin-field quantum key distribution (TF-QKD) elevates the secure key rate from a linear to a square-root dependence on channel loss while preserving measurement-device-independent security. This protocol is uniquely positioned to enable global-scale quantum networks, even under extreme channel loss. While fiber-based TF-QKD implementations have advanced rapidly since its proposal, free-space realizations have remained elusive due to atmospheric turbulence-induced phase distortions. Here, we report the first experimental demonstration of free-space TF-QKD over 14.2 km urban atmospheric channels, surpassing the effective atmospheric thickness -- a critical threshold for satellite compatibility. We achieve a secret key rate exceeding the repeaterless capacity bound, a milestone for practical quantum communication. Our approach eliminates the need for an auxiliary channel to stabilize a closed interferometer, instead leveraging open-channel time and phase control of optical pulses. This work represents a pivotal advance toward satellite-based global quantum networks, combining high-speed key distribution with inherent resistance to real-world channel fluctuations.
Source: arXiv (Cornell University)
Authors: Li, Yu-Huai, Zeng, Ting, Wang, Min-Yan, Jiang, Cong, Lin, Jin, Fu, Hao-Bin, Zheng, Xin-Yang, Chen, Jiu-Peng, Lin, Zeng-Sen, Li, Cheng-Lin, Guan, Jian-Yu, Li, Yang, Shen, Qi, Li, Hao, You, Lixing, Wang, Zhen, Zhou, Fei, Yin, Juan, Liao, Sheng-Kai, Ren, Ji-Gang, Wang, Xiang-Bin, Cao, Yuan, Zhang, Qiang, Peng, Cheng-Zhi, Pan, Jian-Wei
Institutions: State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Jinan Institute of Quantum Technology, Chinese Academy of Sciences, Shanghai Institute of Microsystem and Information Technology, State Key Laboratory of Functional Materials for Informatics, University of Science and Technology of China
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6979340955
Cites:
Cited by:
Related to: