Quantum-improved phase estimation with a displacement-assisted SU(1,1) interferometer

TL;DR

This paper introduces a displacement-assisted SU(1,1) interferometer that enhances phase sensitivity and robustness through local displacement operations, approaching the Heisenberg limit even with photon losses.

Contribution

It proposes a novel displacement-assisted SU(1,1) interferometer that improves phase estimation performance and robustness compared to traditional setups.

Findings

Enhanced phase sensitivity with increased LDO strength.

Performance approaches the Heisenberg limit in ideal conditions.

Robustness against photon losses is significantly improved.

Abstract

By performing two local displacement operations (LDOs) inside an SU(1,1) interferometer, called as the displacement-assisted SU(1,1) [DSU(1,1)], both the phase sensitivity based on homodyne detection and quantum Fisher information (QFI) with and without photon losses are investigated in this paper. In this DSU(1,1) interferometer, we focus our attention on the extent to which the introduced LDO affects the phase sensitivity and the QFI, even in the realistic scenario. Our analyses show that the estimation performance of DSU(1,1) interferometer is always better than that of SU(1,1) interferometer without the LDO, especially the phase precision of the former in the ideal scenario gradually approaching to the Heisenberg limit via the increase of the LDO strength. More significantly, different from the latter, the robustness of the former can be enhanced markedly by regulating and controlling the LDO. Our findings would open an useful view for quantum-improved phase estimation of optical interferometers.