Angular momentum spatial distribution symmetry breaking in Rb by an external magnetic field

Excited state angular momentum alignment – orientation conversion for atoms with hyperfine structure in presence of an external magnetic field is investigated. Transversal orientation in these conditions is reported for the first time. This phenomenon occurs under Paschen Back conditions at intermediate magnetic field strength. Weak radiation from a linearly polarized diode laser is used to excite Rb atoms in a cell. The laser beam is polarized at an angle of π/4 with respect to the external magnetic field direction. Ground state hyperfine levels of the 5S1/2 state are resolved using laser-induced fluorescence spectroscopy under conditions for which all excited 5P3/2 state hyperfine components are excited simultaneously. Circularly polarized fluorescence is observed to be emitted in the direction perpendicular to both to the direction of the magnetic field B and direction of the light polarization E. The obtained circularity is shown to be in quantitative agreement with theoretical predictions.