Sagnac-loop integrated quantum key distribution with weak measurement enhanced fiber-optic sensing for disturbance magnitude and location
Weiqian Zhao, Wenzhao Huang, Zifu Su +5 more
Abstract The deep integration of quantum communication and fiber-optic sensing is pivotal for the development of next-generation multifunctional and highly reliable secure information infrastructure. Here, we present a Sagnac-loop integrated system (SLIS) that, combines ring-based discrete-variable quantum key distribution with fiber-based weak measurement (WM) enhanced sensing and disturbance localization capabilities. In the event of communication interruption due to external disturbances, the SLIS seamlessly switches to perception system, employing interference measurement and WM techniques to monitor channel disturbances. By integrating null-frequencies localization (NFL) mode, the system precisely determines the disturbance location, enabling rapid identification of security vulnerabilities along the link. Experimental results demonstrate that, over a 30 km fiber loop, the SLIS achieves a secure key rate of 25.5 kbps with stable operation and clear scalability toward network expansion. In terms of perception performance, the SLIS exhibits strong capability for both dynamic and quasi-static disturbances. Specifically, the system detects transient impacts and lead zirconate titanate (PZT) driven frequency variations down to 100 Hz, and enables long-distance localization via NFL. For quasi-static disturbances, gravitational changes as small as 100 g are resolved, corresponding to equivalent time-delay variations of 14.4 as inferred from the measured optical response. The SLIS provides a novel technical pathway toward self-diagnosing, robust quantum networks through integrated communication and sensing functionalities.
Quantum Science and Technology•Jun 12, 2026•0 citations