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arXiv · 2310.18525

Polarization vs. magnetic field: competing eigenbases in laser-driven atoms

Nicolás Adrián Nuñez Barreto·Cecilia Cormick·Christian Tomás Schmiegelow
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Abstract

We present experimental results and a theoretical model that illustrate how competing eigenbases can determine the dynamics of a fluorescing atom. In the absence of a magnetic field, the atom can get trapped in a dark state, which inhibits fluorescence. In general, this will happen when the magnetic degeneracy of the ground state is greater than the one of the excited state. A canonical way to avoid optical pumping to dark states is to apply a magnetic field at an angle with respect to the polarization of the exciting light. This generates a competition of eigenbases which manifests as a crossover between two regimes dominated either by the laser or the magnetic field. We illustrate this crossover with fluorescence measurements on a single laser-cooled calcium ion in a Paul trap and find that it occurs at a critical laser intensity that is proportional to the external magnetic field. We contrast our results with numerical simulations of the atomic levels involved and also present a simple theoretical model that provides excellent agreement with experimental results and facilitates the understanding of the dynamics.

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Nicolás Adrián Nuñez Barreto, Cecilia Cormick, Christian Tomás Schmiegelow. 2023-10-27. Polarization vs. magnetic field: competing eigenbases in laser-driven atoms. https://arxiv.org/abs/2310.18525

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