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

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.Comment: 7 pages, 5 figure

Observation of atmospheric scintillation during the 2020 total eclipse in northern Patagonia

During the December 2020 total eclipse we registered time resolved light measurements of incident solar light with VIS-NIR photodiodes in northern Patagonia. Signals compatible with the observation of shadow bands in the 200 s before and after totality were observed. A strong increase in the normalized noise spectral densities of recorded incident radiation near totality suggests the presence of shadow bands. Originally high-altitude balloon measurements and spatial correlation ground measurements were planned, but the harsh climate conditions limited the campaign?s results.Fil: Schmiegelow, Christian Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Drechsler, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Filgueira, Lautaro Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Nuñez Barreto, Nicolás Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Meconi, Franco. No especifíca

Algunos aspectos de la teoría cuasiclásica de ionización atómica por efecto túnel

Fil:Nuñez Barreto, Nicolás Adrián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina