Entangled states of trapped ions allow measuring the magnetic field gradient of a single atomic spin

TL;DR

This paper proposes a method using entangled trapped ions to measure extremely small magnetic field gradients of single atoms, enabling new investigations in atomic and molecular magnetic properties.

Contribution

It introduces a novel technique leveraging entangled ion states to detect magnetic field gradients at unprecedented sensitivity levels.

Findings

Achieves measurement sensitivity of about 10^{-13} Tesla/μm.

Applicable to various ions and atomic ensembles.

Within current ion trap technology capabilities.

Abstract

Using trapped ions in an entangled state we propose detecting a magnetic dipole of a single atom at distance of a few $\mu$m. This requires a measurement of the magnetic field gradient at a level of about 10$^{-13}$ Tesla/$\mu$m. We discuss applications e.g. in determining a wide variation of ionic magnetic moments, for investigating the magnetic substructure of ions with a level structure not accessible for optical cooling and detection,and for studying exotic or rare ions, and molecular ions. The scheme may also be used for measureing spin imbalances of neutral atoms or atomic ensembles trapped by optical dipole forces. As the proposed method relies on techniques well established in ion trap quantum information processing it is within reach of current technology.