Imaging velocity selective resonances in a magnetic field

Abstract

We demonstrate techniques for imaging both magnetic fields and magnetic sublevel distributions using velocityselective Raman transitions in cold 87 Rb and 85 Rb ensembles. When an expanding atom cloud is exposed to counterpropagating laser beams, resonant atom trajectories undergoing Raman transitions are perturbed and result in distinctive features in images of the expanded cloud. If the counterpropagating laser fields couple magnetic sublevels in different hyperfine manifolds, the images provide a spectrograph of sublevel occupation. The techniques are simple to implement and provide a useful, rapid diagnostic tool for cold atom experiments.