Optical pumping enhancement of a free-induction-decay magnetometer

Tools

Hunter, Dominic and Mrozowski, Marcin S. and McWilliam, Allan and Ingleby, Stuart J. and Dyer, Terry E. and Griffin, Paul F. and Riis, Erling (2023) Optical pumping enhancement of a free-induction-decay magnetometer. The Journal of Optical Society of America B, 40 (10). pp. 2664-2673. ISSN 1520-8540 (https://doi.org/10.1364/JOSAB.501086)

[thumbnail of Hunter-etal-JOSAB-2023-Optical-pumping-enhancement-of-a-free-induction-decay-magnetometer]
Preview
 Text. Filename: Hunter_etal_JOSAB_2023_Optical_pumping_enhancement_of_a_free_induction_decay_magnetometer.pdf
Final Published Version
License: Creative Commons Attribution 4.0 logo
Download (6MB)| Preview

Abstract

Spin preparation prior to a free-induction-decay (FID) measurement can be adversely affected by transverse bias fields, particularly in the geophysical field range. A strategy that enhances the spin polarization accumulated before readout is demonstrated, by synchronizing optical pumping with a magnetic field pulse that supersedes any transverse fields by over two orders of magnitude. The pulsed magnetic field is generated along the optical pumping axis using a compact electromagnetic coil pair encompassing a micro-electromechanical systems (MEMS) vapor cell. The coils also resistively heat the cesium vapor to the optimal atomic density without spurious magnetic field contributions as they are rapidly demagnetized to approximately zero field during spin readout. The demagnetization process is analyzed electronically, and directly with a FID measurement, to confirm that the residual magnetic field is minimal during detection. The sensitivity performance of this technique is compared to existing optical pumping modalities across a wide magnetic field range. A noise floor sensitivity of 238 fT/ √Hz was achieved in a field of approximately 50 µT, in close agreement with the Cramér–Rao lower bound predicted noise density of 258 fT/ √Hz.

ORCID iDs

Hunter, Dominic ORCID logoORCID: https://orcid.org/0000-0003-4177-6027, Mrozowski, Marcin S., McWilliam, Allan, Ingleby, Stuart J. ORCID logoORCID: https://orcid.org/0000-0001-7473-9949, Dyer, Terry E., Griffin, Paul F. ORCID logoORCID: https://orcid.org/0000-0002-0134-7554 and Riis, Erling ORCID logoORCID: https://orcid.org/0000-0002-3225-5302;
CORE (COnnecting REpositories)