Experimental Demonstration of a Displacement Measurement of an Optical Beam beyond the Quantum Noise Limit

We experimentally generate a spatially squeezed light beam and realize a small-displacement measurement beyond the quantum noise limit with this squeezed light. Moreover, we measure about −2.2±0.2 dB spatial squeezing and reduce the minimum measurable displacement from 1.17 A to 0.99 A with the signal-to-noise ratio normalized to 1.