Efficient approach for quantum sensing field gradients with trapped ions

TL;DR

This paper presents a quantum sensing protocol using coupled trapped ions to detect spatially varying electric and magnetic fields, achieving high sensitivity through adiabatic and strong coupling techniques.

Contribution

It introduces a novel quantum sensing method with trapped ions, utilizing spin-phonon interactions for enhanced detection of field gradients.

Findings

Adiabatic sensing detects small force differences via ion spin populations.

Method can measure magnetic field gradients independent of magnetic offset.

Strong spin-phonon coupling improves sensitivity, with quantum Fisher information diverging near critical coupling.

Abstract

We introduce quantum sensing protocol for detection spatially varying fields by using two coupled harmonic oscillators as a quantum probe. We discuss a physical implementation of the sensing technique with two trapped ions coupled via Coulomb mediated phonon hopping. Our method relies on using the coupling between the localized ion oscillations and the internal states of the trapped ions which allows to measure spatially varying electric and magnetic fields. First we discuss an adiabatic sensing technique which is capable to detect a very small force difference simply by measuring the ion spin population. We also show that the adiabatic method can be used for detection magnetic field gradient which is independent of the magnetic offset. Second, we show that the strong spin phonon coupling could leads to improve sensitivity to force as well as to phase estimations. We quantify the sensitivity in terms of quantum Fisher information and show that it diverges by approaching the critical coupling.