# Criticality-Enhanced Quantum Sensing in the Anisotropic Quantum Rabi Model

## TL;DR

This paper extends the criticality-enhanced quantum sensing framework to the anisotropic quantum Rabi model, deriving analytical expressions for quantum Fisher information and analyzing the effects of different interaction terms.

## Contribution

It generalizes the dynamic quantum sensing framework to anisotropic models and provides analytical insights into the roles of interaction terms.

## Key findings

- Quantum Fisher information peaks at the isotropic quantum Rabi model.
- Rotating-wave coupling has a greater impact on higher-order corrections.
- Analytical expressions for QFI in anisotropic QRM are derived.

## Abstract

Quantum systems that undergo quantum phase transitions exhibit divergent susceptibility and can be exploited as probes to estimate physical parameters. We generalize the dynamic framework for criticality-enhanced quantum sensing by the quantum Rabi model (QRM) to its anisotropic counterpart and derive the correspondingly analytical expressions for the quantum Fisher information (QFI). We find that the contributions of the rotating-wave and counterrotating-wave interaction terms are symmetric at the limit of the infinite ratio of qubit frequency to field frequency, with the QFI reaching a maximum for the isotropic quantum Rabi model. At finite frequency scaling, we analytically derive the inverted variance of higher-order correction and find that it is more affected by the rotating-wave coupling than by the counterrotating-wave coupling.