Electromagnetic induction imaging with atomic magnetometers: unlocking the low-conductivity regime

TL;DR

This paper demonstrates contactless electromagnetic induction imaging of low-conductivity materials using atomic magnetometers, achieving unprecedented sensitivity and stability suitable for biomedical and material applications.

Contribution

It introduces a novel imaging approach with atomic magnetometers capable of detecting very low conductivities in unshielded environments, surpassing previous methods by over three orders of magnitude.

Findings

Achieved imaging of specimens with conductivity as low as 50 S/m.

Reduced phase noise by a factor of 172 using near-resonant imaging.

Projected sensitivity of 1 S/m for low-conductivity detection.

Abstract

Electromagnetic induction imaging with atomic magnetometers has disclosed unprecedented domains for imaging, from security screening to material characterization. However, applications to low-conductivity specimens -- most notably for biomedical imaging -- require sensitivity, stability, and tunability only speculated thus far. Here, we demonstrate contactless and non-invasive imaging down to 50 S/m using a 50 fT/Hz$^{-1/2}$ $^{87}$Rb radio-frequency atomic magnetometer operating in an unshielded environment and near room temperature. Two-dimensional images of test objects are obtained with a near-resonant imaging approach, which reduces the phase noise by a factor 172, with projected sensitivity of 1 S/m. Our results, an improvement of more than three orders of magnitude on previous imaging demonstrations, push electromagnetic imaging with atomic magnetometers to regions of interest for semiconductors, insulators, and biological tissues.