Device-independent quantum key distribution (DI-QKD) is a key application of the quantum internet. We report the realization of DI-QKD between two single-atom nodes linked by 100-km fibers. To improve the entangling rate, single-photon interference is leveraged for entanglement heralding, and quantum frequency conversion is used to reduce fiber loss. A tailored Rydberg-based emission scheme suppresses the photon recoil effect on the atom without introducing noise. We achieved high-fidelity atom-atom entanglement and positive asymptotic key rates for fiber lengths up to 100 km. At 11 km, 1.2 million heralded Bell pairs were prepared over 624 hours, yielding an estimated extractable finite-size secure key rate of 0.112 bits per event against general attacks. Our results close the gap between proof-of-principle quantum network experiments and real-world applications.
@article{arxiv.2602.09596,
title = {Device-independent quantum key distribution over 100 km with single atoms},
author = {Bo-Wei Lu and Chao-Wei Yang and Run-Qi Wang and Bo-Feng Gao and Yi-Zheng Zhen and Zhen-Gang Wang and Jia-Kai Shi and Zhong-Qi Ren and Thomas A. Hahn and Ernest Y. -Z. Tan and Xiu-Ping Xie and Ming-Yang Zheng and Xiao Jiang and Jun Zhang and Feihu Xu and Qiang Zhang and Xiao-Hui Bao and Jian-Wei Pan},
journal= {arXiv preprint arXiv:2602.09596},
year = {2026}
}
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