Microwave-optical double-resonance vector magnetometry with warm Rb atoms

TL;DR

This paper introduces a room-temperature, unshielded vector magnetometer based on microwave-optical double resonance in warm rubidium atoms, capable of measuring magnetic field direction and magnitude with high accuracy.

Contribution

It demonstrates a novel unshielded, self-calibrating vector magnetometer using magneto-optical double resonance and neural networks at ambient temperature.

Findings

Achieved 1-degree accuracy in magnetic field direction measurement.

Measured magnetic field amplitude near 50 μT with 115 nT accuracy.

Operates without magnetic shielding, suitable for miniaturization.

Abstract

Developing a non-invasive, accurate vector magnetometer that operates at ambient temperature and is conducive to miniaturization and is self-calibrating is a significant challenge. Here, we present an unshielded three-axis vector magnetometer whose operation is based on the angle-dependent relative amplitude of magneto-optical double-resonance features in a room-temperature atomic ensemble. Magnetic-field-dependent double resonance features change the transmission of an optical probe tuned to the D2 optical transition of $^{87}$Rb in the presence of a microwave field driving population between the Zeeman sublevels of the ground state hyperfine levels $F = 1$ and $F = 2$. Sweeping the microwave frequency over all Zeeman sublevels results in seven double-resonance features, whose amplitudes vary as the orientation of the external static magnetic field changes with respect to the optical and microwave field polarization directions. Using a convolutional neural network model, the magnetic field direction is measured in this proof-of-concept experiment with an accuracy of 1{\deg} and its amplitude near 50 $\mu$T with an accuracy of 115 nT.