Precision enhancement in quantum spatial measurement by squeezing-assisted weak-value amplification
ChaoXia Zhang, Yongchao Chen, Gang Chen, Hengxin Sun, Jing Zhang, Kui Liu, Rongguo Yang, Jiangrui Gao · Physical Review Applied · 2024
Precision enhancement is demonstrated in an optical spatial measurement based on a weak-value amplification (WVA) system and splitlike detection, by injecting a ${\mathrm{TEM}}_{10}$ squeezed vacuum beam. We have experimentally realized high-precision optical spatial measurement beyond the shot-noise limit by using squeezing-assisted WVA. Based on the WVA technique, which can amplify the signal by increasing the number of photons that are injected into the interferometer, squeezed-beam injection can reduce the noise level and can further improve the signal-to-noise ratio (SNR). As a result, an SNR improvement of 2 dB, i.e., 1.3 times precision enhancement, can be achieved, and the obtained displacement and tilt sensitivity are $4.96\phantom{\rule{0.2em}{0ex}}\mathrm{fm}/\sqrt{\text{Hz}}$ and $0.39\phantom{\rule{0.2em}{0ex}}\mathrm{prad}/\sqrt{\text{Hz}}$, respectively, by using a 2-dB squeezed-beam injection and 2.6% postselection probability in the WVA process. Our work provides an effective method to accomplish higher precision in quantum spatial measurement, which has potential applications in gravitational wave interferometer calibration, super-resolution quantum imaging, etc.