Advances in Atomic Magnetometry for Ultra-Low-Field NMR and MRI

In this thesis the candidate proposes some technical and fundamental advances for NMR and MRI measurements in the ultra-low field (ULF) regime executed with optical-atomic-magnetometers (OAMs). This regime corresponds to field intensities such to make the nuclei precess at frequencies as low as tens/hundreds Hz. A self-optimized compensation system reduces the magnetic disturbances so to make the magnetometer suited to detect those ULF signals in an unshielded environment. The magnetometer is exploited as a high-sensitivity non-inductive sensor for ULF-NMR signal detection. Besides application in ULF-NMR spectroscopy, the simultaneous analysis of nuclear and atomic precession is used in a novel hybrid setup, which enables the detection of diluted magnetic contaminants. As predominant result an inhomogeneous-magnetic-dressing based (IDEA) technique has been devised enabling the first in-situ ULF-MRI detection by OAMs with sub-millimetric resolution.