Improvement of phase sensitivity in SU(1,1) interferometer via a Kerr nonlinear

TL;DR

This paper presents a theoretical scheme to improve phase sensitivity in SU(1,1) interferometers by incorporating Kerr nonlinear phase shifts, which enhances sensitivity, quantum Fisher information, and reduces photon losses.

Contribution

Introducing Kerr nonlinear phase shifts into SU(1,1) interferometers to significantly enhance phase sensitivity and suppress photon losses compared to linear phase shifts.

Findings

Kerr nonlinear phase shift improves phase sensitivity.

Enhanced quantum Fisher information with nonlinear phase.

Significant suppression of photon losses in the scheme.

Abstract

We propose a theoretical scheme to enhance the phase sensitivity by introducing a Kerr nonlinear phase shift into the traditional SU(1,1) interferometer with a coherent state input and homodyne detection. We investigate the realistic effects of photon losses on phase sensitivity and quantum Fisher information. The results show that compared with the linear phase shift in SU(1,1) interferometer, the Kerr nonlinear case can not only enhance the phase sensitivity and quantum Fisher information, but also significantly suppress the photon losses. We also observe that at the same accessible parameters, internal losses have a greater influence on the phase sensitivity than the external ones. It is interesting that, our scheme shows an obvious advantage of low-cost input resources to obtain higher phase sensitivity and larger quantum Fisher information due to the introduction of nonlinear phase element.