Valentin V. Volchkov, Jahn Rührig, Tilman Pfau, Axel Griesmaier
Demagnetization cooling relies on spin-orbit coupling that brings motional and spin degrees of freedom into thermal equilibrium. In the case of a gas, one has the advantage that the spin degree of freedom can be cooled very efficiently using optical pumping. We investigate demagnetization cooling of a chromium gas in a deep optical dipole trap over a large temperature range and reach high densities up to 5*10^19m^-3. We study the loss mechanism under such extreme conditions and identify excited state collisions as the main limiting process. We discuss that demagnetization cooling has realistic potential of reaching degeneracy by optical cooling only.
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http://arxiv.org/abs/1306.3365
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