Hannover 2013 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 48: Ultracold atoms: Traps and cooling

Q 48.1: Vortrag

Donnerstag, 21. März 2013, 11:00–11:15, A 310

Laser cooling of dense atomic gases by collisional redistribution of radiation — •Anne Saß, Ralf Forge, Peter Moroshkin, and Martin Weitz — Institut für Angewandte Physik der Universität Bonn, Wegelerstraße 8, 53115 Bonn

We study laser cooling of atomic gases by collisional redistribution of fluorescence, a technique applicable to ultradense atomic ensembles of alkali atoms at a few hundred bar of buffer gas pressure. The cooled gas has a density of more than ten orders of magnitude above the typical values in Doppler cooling experiments of dilute atomic gases. In frequent collisions with noble gas atoms in the dense gas system, the energy levels of the alkali atoms are shifted, and absorption of far red detuned incident radiation becomes feasible. The subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a redistribution of the fluorescence. The emitted photons have a higher energy than the incident ones, and the dense atomic ensemble is cooled. We here report on recent experiments of a Rb-noble gas mixture and on the dependency of the cooling effect as a function of different experimental parameters, e.g. buffer gas pressure and incident laser power. For the future, we expect that redistribution laser cooling can also be applied to molecular gas samples.