Adiabatic Sensing Technique for Optimal Temperature Estimation using Trapped Ions

TL;DR

This paper introduces an adiabatic quantum sensing method using trapped ions for precise temperature estimation of phonon modes, effective beyond the Lamb-Dicke regime, and capable of reaching fundamental quantum limits.

Contribution

It presents a novel adiabatic technique for phonon temperature estimation that maps thermal distributions onto spin states, enabling simple measurements and optimal precision.

Findings

Achieves temperature estimation at the quantum Cramér-Rao bound.

Operates effectively beyond the Lamb-Dicke regime.

Uses spin-dependent fluorescence for measurement.

Abstract

We propose an adiabatic method for optimal phonon temperature estimation using trapped ions which can be operated beyond the Lamb-Dicke regime. The quantum sensing technique relies on a time-dependent red-sideband transition of phonon modes, described by the non-linear Jaynes-Cummings model in general. A unique feature of our sensing technique is that the relevant information of the phonon thermal distributions can be transferred to the collective spin-degree of freedom. We show that each of the thermal state probabilities is adiabatically mapped onto the respective collective spin-excitation configuration and thus the temperature estimation is carried out simply by performing a spin-dependent laser fluorescence measurement at the end of the adiabatic transition. We characterize the temperature uncertainty in terms of the Fisher information and show that the state projection measurement saturates the fundamental quantum Cram\'er-Rao bound for quantum oscillator at thermal equilibrium.