Improving phase sensitivity of interferometers by inverse operations

In this study, we propose an improved theoretical model for the phase estimation scheme with inverse operations and compare it with the conventional phase estimation model in terms of the Fisher information and error propagation equation. In addition, we analyse the phase sensitivity of Mach-Zehnder Interferometer (MZI) and SU(1,1) interferometer (SU(1,1)I) with the coherent or squeezed states as input for intensity detection. We also discuss the phase sensitivity of MZI and SU(1,1)I with inverse displaced and inverse squeezed operations for intensity detection, and extensively compare them with and without the inverse operation scheme. Accordingly, we conclude that the phase sensitivity of interferometers can be significantly enhanced by embedding additional inverse operations.