Enhancing the sensitivity of rotation in a multi-atom Sagnac interferometer

TL;DR

This paper explores how multi-partite entangled states can significantly improve the sensitivity of rotation measurements in a multi-atom Sagnac interferometer, achieving Heisenberg-limited precision and highlighting the impact of system size.

Contribution

It introduces a new Hermitian generator for rotation sensitivity analysis and demonstrates how entangled states can enhance quantum Fisher information in such interferometers.

Findings

QFI can scale quadratically with particle number, reaching Heisenberg limit.

QFI depends biquadratically on the ring radius, increasing with size.

Partially and globally entangled states improve rotation sensitivity.

Abstract

We investigate quantum sensing of rotation with a multi-atom Sagnac interferometer and present multi-partite entangled states to enhance the sensitivity of rotation frequency. For studying the sensitivity, we first present a Hermitian generator with respect to the rotation frequency. The generator, which contains the Sagnac phase, is a linear superposition of a z component of the collective spin and a quadrature operator of collective bosons depicting the trapping modes, which enables us to conveniently study the quantum Fisher information (QFI) for any initial states. With the generator, we derive the general QFI which can be of square dependence on the particle number, leading to Heisenberg limit. And we further find that the QFI may be of biquadratic dependence on the radius of the ring which confines atoms, indicating that larger QFI is achieved by enlarging the radius. In order to obtain the square and biquadratic dependence, we propose to use partially and globally entangled states as inputs to enhance the sensitivity of rotation.