Degenerate two-level system in the presence of a transverse magnetic field

L. Margalit, M. Rosenbluh, A. D. Wilson-Gordon

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39 Scopus citations


The effect of a transverse magnetic field (TMF) on the absorption spectra of degenerate two-level systems in the D2 line of 87Rb is investigated both analytically and numerically. We compare the effect of the TMF on the absorption of a σ polarized pump in the Hanle configuration with that of a σ- probe in the presence of a σ+ pump in the pump-probe configuration, and we show that the absorption spectra in both configurations is split in the presence of a TMF and that the splitting is proportional to its magnitude. The population redistribution in the ground state due to the TMF is reinforced by collisional effects, leading to increased splitting of the coherent population trapping (CPT) dip in the absorption spectrum. We explain the appearance of the splitting by setting the quantization axis along the total magnetic field. Then, in the Hanle configuration, the direction of the quantization axis changes as the longitudinal magnetic field is scanned, so that the laser polarization also changes. This leads to the creation of new two-photon detuned Λ subsystems. The evolution of the populations and coherences of the ground-state Zeeman sublevels is illustrated using the angular momentum probability surface. In addition to being split, the CPT dip in the pump-probe configuration is also shifted by the longitudinal magnetic field, so that the effects of the longitudinal and transverse magnetic fields can be distinguished from each other.

Original languageEnglish
Article number033808
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number3
StatePublished - 12 Mar 2013


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