Hannover 2010 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 21: Poster I
Q 21.23: Poster
Dienstag, 9. März 2010, 16:00–19:00, Lichthof
Ultracold fermionic potassium atoms in a CO2 -laser optical dipole trap — •Christian Bolkart, Alexander Gatto, Ondrej Sobora und Martin Weitz — Institut für Angewandte Physik, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstrasse 8, 53111 Bonn
We will report progress in an experiment directed towards realisation of a fermionic potassium Fermi gas with all-optical techniques. The quantum gas will be used for studies of a supersolid phase transition with fermionic atoms in an optical lattice. In our experiment a cold atomic 40K beam emitted from a two-dimensional MOT is used to load a dark magneto optic trap. The density of the trapped atoms is increased by switching to a compressed MOT where we ramp our magnetic field to higher values and reduce the intensity of our repumping laser. We subsequently transfer 106 fermionic potassium atoms in the quasistatic dipole trapping potential realized with a tightly focused CO2-laser beam with wavelength near 10.6 µ m. After 500 ms of plain evaporation the dipole traped atomic cloud is further cooled by forced evaporation, i.e. the potential depth is reduced by lowering the optical power of the CO2-laser. At the final potential depth approximately 40000 atoms remain at a temperature of 200 nK. With the given geometrical trap frequency of the dipole trap and the atom number after evaporation, we estimate T/TF = 0.8.
In the future, we plan to further improve the forced evaporation in order to reach the quantum degenerate regime, i.e. T/TF < 0.5. The present status of the the experiment will be summarised.