Biaxial spatial orientation of atomic angular momentum

Abstract

We experimentally create and theoretically explain a different type of highly anisotropic atomic angular-momentum distribution with two preferential axes. Such a biaxial spatial orientation is created by optical pumping with elliptically polarized light, and measured by the observation of coherent population trapping in a weak external magnetic field. We probe the angular-momentum distribution by the Hanle configuration, and observe two dark resonances at nonzero magnetic fields---the expected signature of the biaxial spatial geometry. A direct method for preparing arbitrarily oriented atomic ensembles is discussed.