Spatial magnetic field mapping with Raman spectra of laser-cooled atoms in free-fall.

For upcoming experiments, we require a linear magnetic field to be applied over the longitudinal extent of an atom's trajectory through a vertically oriented atom interferometer. Additionally, we plan to use magnetically sensitive states. This combination comes at the cost of increased sensitivity to noise in the external field environment and, as a result, the magnetic field must be more carefully characterized and controlled than in a standard atom interferometer. We present our methods to characterize an extended, linear magnetic field environment which can be suitable for making such a system. We perform standard Raman spectroscopy but by adding time resolution to the spectroscopy, we are able to use the expansion of a thermal cloud of atoms to sample a large range along the ballistic atom path with a single spectrum. A small number of these spectra can then be used to map the field along the entire path with better precision than standard Raman spectroscopy. [ABSTRACT FROM AUTHOR]