Enhancing phase sensitivity in Mach-Zehnder interferometer with various detection schemes using SU(1,1) coherent states

TL;DR

This paper investigates how different detection schemes and SU(1,1) coherent states can enhance phase sensitivity in Mach-Zehnder interferometers, achieving quantum limits under optimal conditions.

Contribution

It compares various detection schemes and input states, demonstrating that SU(1,1) coherent states can reach the quantum Cramér-Rao bound in phase sensitivity.

Findings

All detection schemes can reach the QCRB with SU(1,1) coherent states.

Optimal conditions enable maximum phase sensitivity.

Different phase-shift scenarios analyzed for comprehensive understanding.

Abstract

Improving interferometric phase sensitivity is crucial for high-precision measurements in rapidly developing quantum technologies. The Mach-Zehnder interferometer (MZI) is a versatile tool for analyzing this phenomenon. By splitting and recombining a light beam using beam splitters, MZIs allow for precise phase sensitivity analysis using tools like the quantum Cram\'er-Rao bound (QCRB) and the quantum Fisher information (QFI). This paper analyzes the phase sensitivity of a MZI in various scenarios using different detection schemes and input states. We compare the single- and two-parameter quantum estimation and their associated QCRB for three phase-shift situations: in both arms, only in the upper arm (asymmetric), and in both arms symmetrically. We then investigate the phase sensitivity under three detection schemes: intensity difference, single-mode intensity, and balanced homodyne. Additionally, we explore the use of Perelomov and Barut-Girardello coherent states, two types of SU(1,1) coherent states, in all scenarios. Notably, we demonstrate that under optimal conditions, all detection schemes can achieve the QCRB by utilizing SU(1,1) coherent states as input states.