Non-Markovian quantum thermometry

TL;DR

This paper introduces non-Markovian quantum thermometry using a continuous-variable system, achieving a temperature measurement sensitivity that scales linearly with temperature, overcoming traditional divergence issues at low temperatures.

Contribution

It proposes a novel non-Markovian quantum thermometry scheme that leverages quantum criticality to attain the Landau bound for sensing error across all temperature regimes.

Findings

Achieves Landau bound scaling of sensing error with temperature

Utilizes quantum criticality to enhance measurement sensitivity

Effectively avoids divergence of sensing errors at low temperatures

Abstract

The rapidly developing quantum technologies and thermodynamics have put forward a requirement to precisely control and measure the temperature of microscopic matter at the quantum level. Many quantum thermometry schemes have been proposed. However, precisely measuring low temperature is still challenging because the obtained sensing errors generally tend to diverge with decreasing temperature. Using a continuous-variable system as a thermometer, we propose non-Markovian quantum thermometry to measure the temperature of a quantum reservoir. A mechanism to make the sensing error $\delta T$ scale with the temperature $T$ as the Landau bound $\delta T\simeq T$ in the full-temperature regime is discovered. Our analysis reveals that it is the quantum criticality of the total thermometer-reservoir system that causes this enhanced sensitivity. Efficiently avoiding the error-divergence problem, our result gives an efficient way to precisely measure the low temperature of quantum systems.