# Measuring magnetic fields with magnetic field insensitive transitions

## TL;DR

This paper introduces a novel atomic magnetometry technique using clock states insensitive to magnetic field magnitude, leveraging geometric wavefunction dependence, with experimental validation on rubidium atoms.

## Contribution

The paper presents a new magnetometry method based on clock states' geometric properties, offering improved sensitivity over traditional Zeeman-based approaches.

## Key findings

- The method achieves sensitivity scaling inversely with coherence time.
- Experimental demonstration on 87Rb atoms confirms feasibility.
- Clock states provide longer coherence times than Zeeman states.

## Abstract

Magnetometry is an important tool prevalent in many applications such as fundamental research, material characterization and biological imaging. Atomic magnetometry conventionally makes use of two quantum states, the energy difference of which depends linearly on the magnetic field due to the Zeeman effect. The magnetic field is evaluated from repeated measurements of the accumulated dynamic phase between the two Zeeman states in a superposition. Here we propose a magnetometry method that employs a superposition of clock states with energies that do not depend, to first-order, on the magnetic field magnitude. Our method makes use of the geometrical dependence of the clock-states wavefunctions on the magnetic field orientation. We propose detailed schemes for measuring both static and time-varying magnetic fields, and analyze the sensitivity of these methods. We show that, similarly to Zeeman-based methods, the smallest measurable signal scales inversely with the system coherence-time, which for clock transitions is typically significantly longer than for magnetically sensitive transitions. Finally, we experimentally demonstrate our method on an ensemble of optically trapped 87Rb atoms.