Biaxial spatial orientation of atomic angular momentum

We experimentally create and theoretically explain a different type of high ly anisotropic atomic angular-momentum distribution with two preferential a xes. Such a biaxial spatial orientation is created by optical pumping with elliptically polarized light, and measured by the observation of coherent p opulation trapping in a weak external magnetic field. We probe the angular- momentum distribution by the Hanle configuration, and observe two dark reso nances at nonzero magnetic fields-the expected signature of the biaxial spa tial geometry. A direct method for preparing arbitrarily oriented atomic en sembles is discussed. [S1050-2947(99)50203-5].