Collisional thermometry for Gaussian systems

TL;DR

This paper explores a Gaussian collision model for quantum thermometry, analyzing how the Quantum Fisher Information scales with the number of ancillae, and provides insights into the asymptotic behavior and transient effects of correlations.

Contribution

It introduces a Gaussian collision model for quantum thermometry that allows scalable analysis of Quantum Fisher Information, overcoming limitations of qubit-based models.

Findings

QFI scaling can be evaluated for large system sizes.

Transient correlation effects depend on physical parameters.

Asymptotic Fisher information density can be estimated.

Abstract

We investigate a quantum thermometry scheme based collision model with Gaussian systems. A key open question of these schemes concerns the scaling of the Quantum Fisher Information (QFI) with the number of ancillae. In qubit-based implementations this question is difficult to assess, due to the exponentially growing size of the Hilbert space. Here we focus on Gaussian collision models, which allow for the scaling of the QFI to be evaluated for arbitrarily large sizes. This numerical flexibility enables us to explore the thermometric properties of the model for a wide range of configurations. Despite the infinite Markov order of the stochastic process of the model, we provide a simple phenomenological analysis for the behavior of the QFI, estimating the asymptotic Fisher information density and how the transient effects of correlations for an increasing number of ancillae depend on the physical parameters of the model.