Enhanced Long-Distance Weak Signal Transmission Capabilities via Weak Measurement

Reliable detection of weak phase signals under significant channel loss and complex noise environments is a crucial step for practical applications of optical integrated communication and sensing systems. In this letter, we propose and experimentally demonstrate an enhanced long-distance weak signal transmission method assisted by weak measurement. Performing heterodyne detection and light intensity compensation on two nearly symmetric post-selected paths, the method enables real-time estimation of a time-varying phase while maintaining robustness against technical noises proportional to light intensity or photon number, detector common-mode noise, and significant attenuation over long-distance transmission. Experimental results indicate a potential phase sensitivity at the level of 10^-8 rad even with a signal light intensity attenuation of 48.1 dB. Potentially, combining the adaptive adjustment strategy, the method may provide a viable solution in remote weak signal detection and extraction, thereby contributing to optical integrated communication and sensing.