Enhancing Gaussian quantum metrology with position-momentum correlations

TL;DR

This paper introduces a Gaussian quantum metrology protocol utilizing initial position-momentum correlations to enhance parameter estimation, particularly improving low-temperature thermometry and linking purity loss to Fisher information gain.

Contribution

It proposes a novel Gaussian quantum metrology scheme that leverages position-momentum correlations to improve environmental parameter estimation.

Findings

Enhanced thermometry at low temperatures with correlated Gaussian states.

Demonstrated connection between purity loss and Fisher information gain.

Potential resource for quantum thermometry applications.

Abstract

Quantum metrology offers significant improvements in several quantum technologies. In this work, we propose a Gaussian quantum metrology protocol assisted by initial position-momentum correlations (PM). We employ a correlated Gaussian wave packet as a probe to examine the dynamics of Quantum Fisher Information (QFI) and purity based on PM correlations to demonstrate how to estimate the PM correlations and, more importantly, to unlock its potential applications such as a resource to enhance quantum thermometry. In the low-temperature regime, we find an improvement in the thermometry of the surrounding environment when the original system exhibits a non-null initial correlation (correlated Gaussian state). In addition, we explore the connection between the loss of purity and the gain in QFI during the process of estimating the effective environment coupling and its effective temperature.