# Sub-millimetric ultra-low-field MRI detected in situ by a dressed atomic magnetometer

## TL;DR

This paper demonstrates sub-millimetric ultra-low-field MRI using a dressed atomic magnetometer with in situ detection, overcoming gradient compatibility issues and enabling high-resolution imaging in a compact setup.

## Contribution

It introduces a magnetic-dressing technique that restores atomic magnetometer operation in MRI gradients, enabling in situ, high-resolution ULF MRI with a compact device.

## Key findings

- Achieved sub-millimetric resolution MRI with a dressed atomic magnetometer.
- Demonstrated in situ unidimensional imaging of magnetized samples.
- Showed potential for 3D imaging and multi-sensor extensions.

## Abstract

Magnetic Resonance Imaging (MRI) is universally acknowledged as an excellent tool to extract detailed spatial information with minimally invasive measurements. Efforts toward ultra-low-field (ULF) MRI are made to simplify the scanners and to reduce artefacts and incompatibilities. Optical Atomic Magnetometers (OAMs) are among the sensitive magnetic detectors eligible for ULF operation, however they are not compatible with the strong field gradients used in MRI. We show that a magnetic-dressing technique restores the OAMs operability despite the gradient, and we demonstrate sub-millimetric resolution MRI with a compact experimental setup based on an in situ detection. The proof-of-concept experiment produces unidimensional imaging of remotely magnetized samples with a dual sensor, but the approach is suited to be adapted for 3-D imaging of samples magnetized in loco. An extension to multi-sensor architectures is also possible.