Experimental Single-Photon Quantum Key Distribution Surpassing the Fundamental Weak Coherent-State Rate Limit
Quantum key distribution (QKD) offers a secure means of communication based on the laws of quantum physics. Despite its remarkable advancements, the current reliance of QKD on attenuated coherent (laser) light sources has imposed a fundamental limit on the secure key rate (SKR) per channel use. This constraint stems from the scarcity of single-photon components within coherent light, inherently bounded by a maximum of 1/e. Here, we report comprehensive demonstrations of single-photon-source-based high-rate QKD, surpassing the fundamental SKR limit imposed by the weak coherent light. By employing an on-demand, bright single-photon source with an efficiency of 0.71(2), coupled with narrow-bandwidth filtering and random polarization modulation, we demonstrated a field QKD trial over a 14.6(1.1) dB-loss free-space urban channel, achieving a SKR of 1.08×10^{-3} bits per pulse. This SKR surpasses the practical limit of weak coherent-light-based QKD by 79%. These findings unequivocally demonstrate the superior performance of single-photon sources over weak coherent light for QKD applications, marking a pivotal stride towards realizing a global quantum internet.
Authors
- Runze Liu (ORCID: https://orcid.org/0000-0002-1334-4094)
- Jun-Yi Zhao (ORCID: https://orcid.org/0009-0004-7151-687X)
- Sheng‐Kai Liao (ORCID: https://orcid.org/0000-0002-4184-9583)
- Xing Ding (ORCID: https://orcid.org/0000-0002-4724-215X)
- Chao‐Yang Lu (ORCID: https://orcid.org/0000-0002-8227-9177)
- Feihu Xu
- Gao‐Qiang Wang
- Yang Li (ORCID: https://orcid.org/0000-0001-5989-4326)
- Yong-Heng Huo (ORCID: https://orcid.org/0000-0002-0310-3078)
- Li‐Kang Zhang (ORCID: https://orcid.org/0000-0003-3757-8116)
- Yuan Cao (ORCID: https://orcid.org/0000-0002-0354-2855)
- Chengzhi Peng (ORCID: https://orcid.org/0000-0001-8199-0955)
- Mo-Chi Xu
- Yang Zhang (ORCID: https://orcid.org/0000-0002-8591-9598)
- Hui Wang (ORCID: https://orcid.org/0000-0003-1211-1771)
- Zhen Ning (ORCID: https://orcid.org/0000-0002-2901-2991)
- Geng-Yan Zou
- Yu-Ming He
- Yong-Peng Guo
- Jian-Wei Pan
Institutions
- University of Science and Technology of China (CN)
- Hefei National Center for Physical Sciences at Nanoscale (CN)
- Beijing Academy of Quantum Information Sciences (CN)
Publication Details
- Journal
- Physical Review Letters
- Published
- 2025-05-29
- DOI
- https://doi.org/10.1103/physrevlett.134.210801
- Citations
- 18
- Primary Topic
- Quantum Information and Cryptography
- Type
- article
- Field-Weighted Citation Impact
- 44.66
Funders
- Shanghai Science and Technology Development Foundation
- National Natural Science Foundation of China
- Science and Technology Commission of Shanghai Municipality
- Key Technology Research and Development Program of Shandong
- National Key Research and Development Program of China