Magnetic-field-induced alignment-to-orientation conversion in sodium

Abstract

We report a detailed investigation of excited-state alignment-to-orientation conversion in the presence of an external magnetic field. This counterintuitive phenomenon occurs under intermediate-coupling conditions. A weak, linearly polarized, cw laser beam was used to excite and align the Na 3${\mathit{P}}_{3/2}$ state in an atomic beam along the z direction. The degree of circular polarization of the resulting fluorescence was detected along the z direction as a function of magnetic-field strength. The spectrally integrated transitions originating from individual F levels of the 3${\mathit{S}}_{1/2}$ state yield a maximum circular-polarization fraction of \ensuremath{\sim}40%; integrating the circular polarization over all the allowed 3${\mathit{S}}_{1/2}$-3${\mathit{P}}_{3/2}$ transitions gives rise to an \ensuremath{\sim}8% effect. The results are predicted by the Breit formula, which is in excellent agreement with our observations.