Strongly coupled fermionic probe for nonequilibrium thermometry

TL;DR

This paper investigates the measurement sensitivity of a strongly coupled fermionic probe for nonequilibrium thermometry, revealing non-Markovian effects that enhance quantum Fisher information and proposing optimal interrogation times.

Contribution

It introduces a detailed analysis of non-Markovian dynamics in fermionic thermometry, showing how they can be exploited to improve measurement sensitivity and identifying optimal measurement times.

Findings

QFI shows non-monotonic behavior due to non-Markovian effects

Maximum QFI rate occurs at a finite time t*

Collective fermionic probes can enhance measurement precision

Abstract

We characterise the measurement sensitivity, quantified by the Quantum Fisher Information (QFI), of a single-fermionic thermometric probe strongly coupled to the sample of interest, a fermionic bath, at temperature $T$. For nonequilibrium protocols, in which the probe is measured before reaching equilibrium with the sample, we find new behaviour of the measurement sensitivity arising due to non-Markovian dynamics. First, we show that the QFI displays a highly non-monotonic behaviour in time, in contrast to the Markovian case where it grows monotonically until equilibrium, so that non-Markovian revivals can be exploited to reach a higher QFI. Second, the QFI rate is maximised at a finite interrogation time $t^*$, which we characterize, in contrast to the solution $t^* \rightarrow 0$ known in the Markovian limit [Quantum 6, 869 (2022)]. Finally, we consider probes make up of few fermions and discuss different collective enhancements in the measurement precision.