Isotropic magnetometry with simultaneous excitation of orientation and alignment CPT resonances

TL;DR

This paper introduces a polarization modulation scheme for atomic magnetometers that simultaneously excites orientation and alignment CPT resonances, effectively eliminating dead zones and maintaining high sensitivity regardless of magnetic field orientation.

Contribution

The authors demonstrate a simple method to eliminate dead zones in atomic magnetometers by simultaneously exciting orientation and alignment CPT resonances using polarization modulation.

Findings

Achieved narrow, high-contrast CPT peaks in all orientations.

Eliminated systematic effects related to non-linear Zeeman splitting.

Maintained high sensitivity regardless of magnetic field orientation.

Abstract

Atomic magnetometers have very high absolute precision and sensitivity to magnetic fields but suffer from a fundamental problem: the vectorial or tensorial interaction of light with atoms leads to "dead zones", certain orientations of magnetic field where the magnetometer loses its sensitivity. We demonstrate a simple polarization modulation scheme that simultaneously creates coherent population trapping (CPT) in orientation and alignment, thereby eliminating dead zones. Using $^{87}$Rb in a 10 Torr buffer gas cell we measure narrow, high-contrast CPT transparency peaks in all orientations and also show absence of systematic effects associated with non-linear Zeeman splitting.