Higher‐Order Spatially Squeezed Beam for Enhanced Spatial Measurements

Abstract

Abstract A scheme is proposed to realize high‐precision spatial measurement of laser beams beyond quantum limit using a novel quantum state called the order spatially squeezed state, which is the combination of a bright mode coherent state and squeezed vacuum mode state. An effective technique for the generation of a rectangular shape higher‐order mode squeezed light with a maximum mode order of 5 is experimentally demonstrated using a doubling resonated optical parametric amplifier. Furthermore, the fourth order tilt‐ and displacement‐squeezed beams are constructed and used to perform spatial tilt and displacement measurements, thereby improving the signal‐to‐noise ratio by 10 and 8.6 dB compared to the mode. The results indicate that high‐order spatially squeezed states enhance measurement precision beyond the shot noise limit and are more prominent in back‐action noise reduction. High‐precision spatial measurement has potential practical applications in high‐sensitivity atomic force microscope and super‐resolution quantum imaging.