Qubit-assisted thermometry of a quantum harmonic oscillator

TL;DR

This paper demonstrates that high-precision temperature estimation of a quantum harmonic oscillator can be achieved using qubit-based quantum estimation techniques, with near-optimal measurements in relevant experimental models.

Contribution

It introduces two qubit-boson coupling models for quantum thermometry and shows population measurements on the qubit are nearly optimal for temperature estimation.

Findings

High-precision temperature estimation achievable with qubit measurements.

Population measurements are near optimal across various temperatures.

Models are relevant to current experimental control of mesoscopic systems.

Abstract

We use the theory of quantum estimation in two different qubit-boson coupling models to demonstrate that the temperature of a quantum harmonic oscillator can be estimated with high precision by quantum-limited measurements on the qubit. The two models that we address embody situations of current physical interest due to their connection with ongoing experimental efforts on the control of mesoscopic dynamics. We show that population measurements performed over the qubit probe are near optimal for a broad range of temperatures of the harmonic oscillator