Quantum phase estimation with a stable squeezed state

Phase estimation of optical field is a vital measurement strategy that can be used to perform accurate measurements of various physical quantities. Phase estimation precision can be greatly enhanced by using the nonclassical state such as squeezed state and entangled state. Therefore, we addressed the generation of a stable squeezed state through locking the pump laser of non-degenerate optical parametric amplifier to a high finesse Fabry–Perot cavity based on an improved cascade Pound–Drever–Hall frequency stabilization strategy. Then the obtained squeezed state is used as the probe state of quantum phase estimation and its precision is enhanced from 9.3 E-5 (shot-noise-limit) to 4.2 E-5 at the optimal phase with a given average photon number.