München 2004 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 38: Poster Fallen und Kühlung

Q 38.11: Poster

Donnerstag, 25. März 2004, 14:00–16:00, Schellingstr. 3

Transverse confinement effects in stochastic cooling of trapped atoms. — •Denis Ivanov and Sascha Wallentowitz — Fachbereich Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany.

The operation of stochastic cooling of trapped atoms [1] has been studied for a 3D isotropic harmonic potential. The change of energy due to a single cooling step has been obtained in terms of quantum-statistical averages. Contributions in the motion parallel to the control-laser beam direction contain the back-action noise due the employed measurement and noise due to fluctuations of the number of atoms in the control beam [2]. Furthermore, having a control-laser with finite beam-waist, an indirect measurement of the transverse atomic coordinate with the corresponding reduction of the quantum state are carried out during the cooling step. This quantum effect introduces additional noise in the kinetic energy and depends both on the size and on the shape of the beam-waist [3]. In the case, where the thermal wavelength of atoms is smaller than the average interatomic distance, the indistinguishability of atoms can be discarded and the energy change is expressed in terms of geometrical characteristics and temperature. Given these results, a boundary between cooling and heating can be established in dependence on geometrical parameters.

[1] M.G. Raizen et al., Phys. Rev. A 58, 4757 (1998).

[2] D. Ivanov et al., Phys. Rev. A 67, 061401(R) (2003).

[3] D. Ivanov and S. Wallentowitz, J. Opt. B (submitted).