Degenerate two- and three-level systems in presence of longitudinal and transverse magnetic fields

We discuss the effect of static and time-dependent longitudinal and transverse magnetic fields on degenerate two-level and three-level systems in Rb atomic vapor. The effect of a transverse magnetic field (TMF) on the absorption spectra of degenerate two-level systems in the D-2 line of Rb-87 is investigated both analytically and numerically. We compare the effect of the TMF on the absorption of a sigma polarized pump in the Hanle configuration with that of a sigma(-) probe in the presence of a sigma(+) pump in the pump-probe configuration, and show that the absorption spectra in both configurations is split in the presence of a TMF and that the splitting is proportional to the magnitude of the TMF. Coherent population trapping (CPT) transients induced by a modulated longitudinal magnetic field (LMF) are investigated theoretically for a realistic three-level. system in the D-1 line of Rb-87. The contributions to the transient probe absorption from the various subsystems that comprise the realistic atomic system are examined and the absorption of each. subsystem is compared to that of a simple. system. We also present theoretical results for CPT transients induced by a modulated TMF. The application of a TMF leads to the appearance of new. subsystems, the creation of new dark states and the rearrangement of the population among the Zeeman sublevels. We show that transients appear as the system is switched between various steady-state situations and we identify the various components of the total probe absorption.