Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 56: Ultracold atoms and molecules II (with Q)

A 56.2: Talk

Friday, March 21, 2014, 14:15–14:30, DO26 208

Efficient demagnetization cooling and its limits — •Jahn Rührig, Tobias Bäuerle, Tilman Pfau, and Axel Griesmaier — 5. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, Stuttgart, 70569 , Germany

We present the latest data on the demagnetization cooling of a dipolar chromium gas and discuss the limitations regarding reabsorption of optical pumping photons and light assisted collisions. Demagnetizaiton cooling utilizes dipolar relaxations that couple the internal degree of freedom (spin) to the external (angular momentum) to efficiently cool an atomic cloud [1]. Optical pumping into a dark state constantly recycles the atoms that were promoted to higher spin states. The net energy taken away by a single photon is very favorable as the lost energy per atom is the Zeeman energy rather than the recoil energy. The cooling scheme was proposed by Kastler already in 1950 [2] and demonstrated in a proof of principle experiment in 2006 [3].

[1]:S. Hensler et al. , Europhys. Lett. 71,918 (2005).

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

[3]:M. Fattori et al. , Nature Physics 2, 765 (2006).