Yun Peng

Photon sensors have lots of applications in our productive life, from inspection of steel building structures to early disease screening in preventive medicine. However, the precision of these sensors is limited by the shot-noise limit (SNL). Fortunately, previous studies have shown that quantum technology not only has better resolution than traditional sensing methods, but also can achieve ultra-high precision that breaks the SNL. Here, a new fiber salinity sensing method with quantum-limited precision is demonstrated by applying the single photon interferometer. A novel detection method is designed and implemented by using the Fisher information analysis. And the precision is defined as the estimation error of the single photon transmittance. The salinity sensitivity of the single photon interferometer is about -0.00053 /‰ with a good linearity. The salinity resolution of the proposed fiber salinity sensor is 0.062 ‰. And the detection precision is beyond the SNL. This work demonstrates that the introduction of quantum resources has opened a new door for high performance detection technology.