Yu Yafei

Integrating fiber optic sensing and disturbance localization technologies with QKD network systems enables the communication system to detect external interferences and achieve efficient, multifunctional integration. The main advantage of this integration lies in the use of fiber optic sensing and disturbance localization technologies, which not only allow the system to monitor potential external interferences that could affect the communication link but also provide real-time localization of their sources. By introducing this sensing capability, the communication system can respond quickly to sudden events and make necessary adjustments, effectively ensuring the stability and security of the communication. Moreover, the hybrid system that integrates sensing, communication, and localization functions enables these capabilities to work in synergy within the same network. Specifically, the system can flexibly switch between communication, sensing, and localization modes according to the actual needs of the network. For instance, during communication, the system can switch to sensing mode to monitor the status of communication lines in real-time, perform dynamic interference detection and localization, and ensure that the communication signal is not affected by external disturbances. In case of network anomalies or interference, the system can quickly switch to localization mode, identify the issue, and resolve it, ensuring intelligent, flexible responses that optimize communication efficiency and security. In addition, integrating communication, sensing, and localization functions into a single system significantly reduces the need for additional equipment and resources. For example, shared channels and equipment not only lower the overall cost of the system but also avoid unnecessary resource waste caused by redundancy between different subsystems. As multi-functional integration progresses, the system becomes more compact, reducing the complex coupling between subsystems in traditional systems, thus improving overall performance and scalability. In this work, we propose a hybrid system based on the Sagnac loop structure, successfully integrating QKD, fiber optic weak measurement sensing, and zero-frequency disturbance localization technologies. Experimental validation of this system demonstrates that the three functions can work efficiently in tandem, fulfilling different roles in various application scenarios. In particular, while performing QKD communication tasks, the system can monitor the communication lines in real-time using fiber optic weak measurement technology, and use disturbance localization technology to identify and locate potential sources of interference. By integrating these technologies, the system preserves QKD's security and stability while boosting communication efficiency through sensing and localization, ensuring reliable quantum communication in complex environments. The core innovation of this research lies in the effective integration of the QKD system and fiber optic sensing system through the special Sagnac loop optical structure. The Sagnac loop itself possesses self-alignment and phase compensation advantages, which allow the QKD system to maintain high stability without external compensation, while enabling the sensing system to accurately measure small phase changes. This structure simplifies quantum communication devices, reduces system complexity, and enables seamless integration of fiber optic sensing for multifunctional applications.