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Entangling Quantum Memories through a 420 km Long Fiber

Xi-Yu Luo1,2,3,*, Chao-Yang Wang1,2,3,*, Ming-Yang Zheng4,3,*, Bin Wang1,2,3, Jian-Long Liu1,2,3, Bo-Feng Gao4, Jun Li1,2,3, Zi Yan1,2,3, Qiao-Mu Ke1,2,3 et al.

Da Teng1,2,3, Rui-Chun Wang5, Jun Wu5, Jia Huang6, Hao Li6, Li-Xing You6, Xiu-Ping Xie4,3, Feihu Xu1,2,3, Qiang Zhang1,2,3,4, Xiao-Hui Bao1,2,3, and Jian-Wei Pan1,2,3

  • *These authors contributed equally to this work.
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Phys. Rev. Lett. 137, 070801 – Published 11 August, 2026

DOI: https://doi.org/10.1103/ccd6-rf1s

Abstract

Long-distance matter-matter entanglement is pivotal for scalable quantum communication, distributed quantum computing, and sensing. In this Letter, we report entanglement between two atomic ensemble quantum memories over 420 km. We employ the Duan-Lukin-Cirac-Zoller (DLCZ) scheme for remote entanglement generation and convert photons emitted from the memories to telecom S band that enable us to harness ultralow transmission loss in fiber. We stabilize a photon’s relative phase between the two memories using full-time far-off-resonant locking to reduce high-frequency noise and intermittent dual-band locking to compensate low-frequency drift jointly. Furthermore, we demonstrate that the memory-memory entangling probability beats the repeaterless channel capacity for direct entanglement distribution. Our experiment provides a test bed of studying quantum network applications beyond metropolitan scale.

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Phys. Rev. Lett. 137, 070801– Published 11 August, 2026
  • Received 15 February 2026
  • Revised 10 May 2026
  • Accepted 9 June 2026
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