Hannover 2013 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 48: Ultracold atoms: Traps and cooling

Q 48.4: Talk

Thursday, March 21, 2013, 11:45–12:00, A 310

Efficient demagnetization cooling and its limits — •Valentin V Volchkov, Jahn Rührig, Matthias Wenzel, Tilman Pfau, and Axel Griesmaier — 5. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, Stuttgart, 70569 , Germany

Demagnetization cooling of an atomic sample arises from laser cooling of the internal degree of freedom (optical pumping) and the rethermalization of the internal and the external degrees of freedom via dipolar relaxation [1]. It is a cooling scheme that was proposed by Kastler already in 1950 [2] and demonstrated in a proof of principle experiment in 2006 [3]. Here, we present the extension of this work to a larger temperature range. Deep optical potential and strong confinement are used to start the demagnetization cooling at a temperature of T≈ 100 µ K. Active magnetic field stabilization allows to circumvent limitation associated with magnetic field fluctuations at temperatures T<10µ K. Finally, we discuss the reabsorption of scattered light and its effect on the lowest attainable temperature with this technique.

[1]:S. Hensler, A. Greiner, J. Stuhler and T. Pfau, Europhys. Lett. 71, 918 (2005)

[2]:A. Kastler, Le Journal de Physique et le Radium 11, 255 (1950).

[3]:M. Fattori, T. Koch, S. Goetz, A. Griesmaier, S. Hensler, J. Stuhler, T. Pfau, Nature Physics 2, 765 (2006)