Effects of loss on the phase sensitivity with parity detection in an SU(1,1) interferometer

TL;DR

This paper analyzes how loss impacts phase sensitivity in an SU(1,1) interferometer using parity detection, showing it can outperform classical limits with minimal loss but degrades with increased loss, especially compared to other detection methods.

Contribution

It provides a theoretical comparison of parity detection with homodyne and intensity detection under loss in SU(1,1) interferometers, highlighting its advantages and limitations.

Findings

Parity detection slightly better than others without loss

Sensitivity decreases with loss but can beat shot-noise limit

Parity detection performs worse with significant loss for certain inputs

Abstract

We theoretically study the effects of loss on the phase sensitivity of an SU(1,1) interferometer with parity detection with various input states. We show that although the sensitivity of phase estimation decreases in the presence of loss, it can still beat the shot-noise limit with small loss. To examine the performance of parity detection, the comparison is performed among homodyne detection, intensity detection, and parity detection. Compared with homodyne detection and intensity detection, parity detection has a slight better optimal phase sensitivity in the absence of loss, but has a worse optimal phase sensitivity with a significant amount of loss with one-coherent state or coherent $\otimes$ squeezed state input.