Zero-field optical magnetometer based on spin-alignment

TL;DR

This paper introduces a zero-field optical magnetometer based on spin-alignment, utilizing linear polarization rotation to measure magnetic fields with high sensitivity, and demonstrates its potential for medical imaging applications.

Contribution

A novel zero-field magnetometry technique using spin-alignment and polarization rotation, with analytical modeling and experimental validation for biomedical signal detection.

Findings

Good agreement between theory and experiment

High sensitivity and bandwidth characterized

Successful detection of synthetic cardiac signals

Abstract

Optically-pumped magnetometers are an important instrument for imaging biological magnetic signals without the need for cryogenic cooling. These magnetometers are presently available in the commercial market and utilize the principles of atomic alignment or orientation, enabling remarkable sensitivity and precision in the measurement of magnetic fields. This research focuses on utilizing a spin-aligned atomic ensemble for magnetometry at zero-field. A novel approach is introduced, which involves evaluating how the linear polarization of light rotates as it passes through the atomic vapor to null the magnetic field. Analytical expressions are derived for the resulting spin alignment and photodetection signals. Experimental results are provided, demonstrating good agreement with the theoretical predictions. The sensitivity and bandwidth of the magnetometer are characterized based on the detected polarization rotation signal. Lastly, the practical utility of the magnetometer for medical applications is demonstrated by successfully detecting a synthetic cardiac signal.