Microcomb-driven large-scale fully connected quantum network.

Wang, Fang-Xiang; Zheng, Sheng-Teng; Huang, Long; Zhang, Guo-Wei; Wang, Guang-Shu; Ding, Wen-Jing; Wang, Ze-Hao; Wang, Shuang et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Fully connected quantum networks enable simultaneous connection of every user to every other user and are a highly versatile and robust networking architecture. However, the scalability of such networks remains a great challenge for practical applications. Here we construct a large-scale fully connected quantum network founded on two-photon Hong-Ou-Mandel (HOM) interference, where user-to-user security is guaranteed even with an untrusted network provider. Using integrated soliton microcomb (SMC) and photonic encoding chips, we realize precise, massively parallel frequency generation and locking, high-visibility HOM interference and measurement-device-independent (MDI) quantum key distribution. The proposed architecture enables a fully connected quantum network over 200 kilometers with strict information-theoretic security via an untrusted network provider. The implemented networking architecture paves the way for large-scale fully connected MDI quantum networks across metropolitan and intercity regions.