High signal to noise absorption imaging of alkali atoms at moderate magnetic fields

TL;DR

This paper introduces an improved absorption imaging technique for alkali atoms at moderate magnetic fields, enabling accurate measurement of atomic density in Bose-Einstein condensates by using a four-level scheme with two laser frequencies.

Contribution

The authors develop a novel four-level absorption imaging scheme that works effectively at moderate magnetic fields, applicable to all alkali-like species, enhancing imaging accuracy.

Findings

Successfully applied to $^{39}$K Bose-Einstein condensate

Allows extraction of atomic column density with improved accuracy

Applicable to various alkali-like atomic species

Abstract

We present an improved scheme for absorption imaging of alkali atoms at moderate magnetic fields, where the excited state is well in the Paschen-Back regime but the ground state hyperfine manifold is not. It utilizes four atomic levels to obtain an approximately closed optical cycle. With the resulting absorption of the corresponding two laser frequencies we extract the atomic column density of a $^{39}$K Bose-Einstein condensate. The scheme can be readily applied to all other alkali-like species.