Device-independent quantum key distribution over 100 km with single atoms.

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Title: Device-independent quantum key distribution over 100 km with single atoms.
Authors: Lu, Bo-Wei (AUTHOR), Yang, Chao-Wei (AUTHOR), Wang, Run-Qi (AUTHOR), Gao, Bo-Feng (AUTHOR), Zhen, Yi-Zheng (AUTHOR), Wang, Zhen-Gang (AUTHOR), Shi, Jia-Kai (AUTHOR), Ren, Zhong-Qi (AUTHOR), Hahn, Thomas A. (AUTHOR), Tan, Ernest Y.-Z. (AUTHOR), Xie, Xiu-Ping (AUTHOR), Zheng, Ming-Yang (AUTHOR), Jiang, Xiao (AUTHOR), Zhang, Jun (AUTHOR), Xu, Feihu (AUTHOR), Zhang, Qiang (AUTHOR), Bao, Xiao-Hui (AUTHOR), Pan, Jian-Wei (AUTHOR)
Source: Science. 2/5/2026, Vol. 391 Issue 6785, p592-597. 6p.
Subjects: Quantum entanglement, Fiber optics, Optical wavelength conversion, Atoms, Rydberg states, Quantum communication
Abstract: 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–kilometer (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. Editor's summary: A robust and secure quantum internet will be reliant on device-independent quantum key distribution between parties over long distances. Such protocols have so far been limited to small-scale proof-of-principle demonstrations. Lu et al. used a pair of trapped single Rydberg atoms separated by up to 100 kilometers of optic fiber. Manipulating the state of the trapped atoms and using a single-photon interference protocol resulted in heralded entanglement between the two nodes and the ability to distribute quantum keys at metropolitan distances. This approach closes the gap between proof-of-principle quantum network experiments and real-world applications in quantum communication. —Ian S. Osborne [ABSTRACT FROM AUTHOR]
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Database: Psychology and Behavioral Sciences Collection
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Abstract: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–kilometer (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. Editor's summary: A robust and secure quantum internet will be reliant on device-independent quantum key distribution between parties over long distances. Such protocols have so far been limited to small-scale proof-of-principle demonstrations. Lu et al. used a pair of trapped single Rydberg atoms separated by up to 100 kilometers of optic fiber. Manipulating the state of the trapped atoms and using a single-photon interference protocol resulted in heralded entanglement between the two nodes and the ability to distribute quantum keys at metropolitan distances. This approach closes the gap between proof-of-principle quantum network experiments and real-world applications in quantum communication. —Ian S. Osborne [ABSTRACT FROM AUTHOR]
ISSN:00368075
DOI:10.1126/science.aec6243