Enhanced precision bound of low-temperature quantum thermometry via dynamical control

TL;DR

This paper demonstrates that dynamical control of a quantum probe can significantly improve low-temperature thermometry, achieving a temperature-independent relative error bound and enhancing measurement precision in quantum sensing applications.

Contribution

It introduces a method of periodic modulation of quantum probes to maximize quantum Fisher information, leading to improved low-temperature measurement accuracy.

Findings

Periodic modulation increases quantum Fisher information.

Achieves temperature-independent relative error bound.

Enhances precision in quantum thermometry and sensing.

Abstract

High-precision low-temperature thermometry is a challenge for experimental quantum physics and quantum sensing. Here we consider a thermometer modelled by a dynamically-controlled multilevel quantum probe in contact with a bath. Dynamical control in the form of periodic modulation of the energy-level spacings of the quantum probe can dramatically increase the maximum accuracy bound of low-temperatures estimation, by maximizing the relevant quantum Fisher information. As opposed to the diverging relative error bound at low temperatures in conventional quantum thermometry, periodic modulation of the probe allows for low-temperature thermometry with temperature-independent relative error bound. The proposed approach may find diverse applications related to precise probing of the temperature of many-body quantum systems in condensed matter and ultracold gases, as well as in different branches of quantum metrology beyond thermometry, for example in precise probing of different Hamiltonian parameters in many-body quantum critical systems.