Optimizing the phase sensitivity of Michelson interferometer with two-mode squeezed coherent input in the presence of loss and noise

A Michelson-type interferometer with two-mode squeezed coherent state input is considered. Such an interferometer has a better phase sensitivity over the shot-noise limit by a factor of $e 2 r$⁠, where r is the squeezing parameter [Phys. Rev. A 102, 022614 (2020)]. We show that when photon loss and noise in the two arms are asymmetric, an optimal choice of the squeezing angle can allow improvement in phase sensitivity without any increase in input or pump power. In particular, when loss occurs only in one arm of the interferometer, we can have improvement in phase sensitivity for photon loss up to 80%. Hence, a significant improvement can be made in several applications such as LiDAR, gyroscopes, and measuring refractive indices of highly absorptive/reflective materials.