An atomic compass -- detecting 3D magnetic field alignment with vector vortex light

Abstract

We describe and demonstrate how 3D magnetic field alignment can be inferred from single-shot absorption images of an atomic cloud. While optically pumped magnetometers conventionally rely on temporal measurement of the Larmor precession of atomic dipoles, here cold atomic vapours provide a spatial interface between vector light and external magnetic fields. Using a vector vortex beam, we inscribe structured atomic spin polarisation in a cloud of cold rubidium atoms, and record images of the resulting absorption patterns. The spherical alignment can be deduced with spatial Fourier analysis. This effect not only raises the prospect of a conceptually new approach to detecting magnetic fields, but, more generally, demonstrates how introducing spatial phases between atomic energy levels can translate transient effects to the spatial domain.

Visualization of magnetic fields with cylindrical vector beams in a warm atomic vapor

“…Recent works on chip-scale VBs generation [59] and atomic components [60][61][62] would be an exciting next step for realizing miniaturization. We also note that similar effects are seen in related work in the diamond (nitrogen-vacancy center) [63] and cold atoms [47] carried out, confirming the suitability of VBs for visual observation of the alignment of magnetic fields in 3D space.…”

“…In the former case, a weak TMF closes the EIT transitions, thereby generating phase-dependent dark states and, in turn, spatially dependent transparency. As the spatially observed transparency patterns and applied magnetic fields are directly coupled, this offers the possibility of detecting magnetic fields from absorption profiles [46,47].…”