Phase estimation via delocalized photon subtraction operation inside the SU(1,1) interferometer

TL;DR

This paper introduces a delocalized photon subtraction operation inside an SU(1,1) interferometer, enhancing phase measurement precision and robustness against photon loss compared to localized methods.

Contribution

It proposes a novel D-PSO scheme within the SU(1,1) interferometer, demonstrating improved phase sensitivity and loss resistance over existing localized photon subtraction techniques.

Findings

D-PSO improves measurement accuracy of SU(1,1) interferometer.

D-PSO enhances robustness against internal photon loss.

Phase sensitivity approaches the quantum Cramér-Rao bound.

Abstract

We propose a theoretical scheme to improve the precision of phase measurement using intensity detection by implementing delocalized photon subtraction operation (D-PSO) inside the SU(1,1) interferometer, with the coherent state and the vacuum state as the input states. We compare the phase sensitivity and the quantum Fisher information between D-PSO and localized photon subtraction operation (L-PSO) under both ideal and photon-loss cases. It has been found that the D-PSO can improve the measurement accuracy of the SU(1,1) interferometer and enhance its robustness against internal photon loss. And it can cover and even exceed the advantages of the L-PSO on two modes, respectively. In addition, by comparing the standard quantum limit, the Heisenberg limit and quantum Cram\'er-Rao bound, we find that the phase sensitivity of the D-PSO can get closer to the quantum Cram\'er-Rao bound and has the ability to resist internal loss.