München 2004 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 21: Poster Quantengase

Q 21.12: Poster

Dienstag, 23. März 2004, 14:00–16:00, Schellingstr. 3

Bose-Einstein condensation in a single-beam dipole trap and an all-optical atom laser — •Carsten Geckeler, Giovanni Cennini, Gunnar Ritt, and Martin Weitz — Physikalisches Institut, Tübingen, Germany

We have created a Bose-Einstein condensate (BEC) by direct evaporative cooling of ⁸⁷Rb atoms in a quasistatic optical dipole trap formed by a focused single running CO₂-laser beam with wavelength near 10.6 µ m. About 4× 10⁶ atoms are loaded from a magneto-optical trap into the dipole trap. Forced evaporative cooling is achieved by continously lowering the trap depth, and generates a F = 1 spinor condensate with 12 000 atoms. The phase transition occurs at a temperature of 180 nK. Further, we have realized a BEC in the m_F = 0 spin projection by applying a moderate magnetic field gradient during evaporation. With this field gradient activated, typically 7000 atoms condense into the m_F = 0 component alone. The chemical potential of the realized condensate is first order insensitive to magnetic field fluctuations. Finally, a collimated and monoenergetic beam of atoms can be extracted from the BEC by smoothly lowering the dipole trapping potential to form an all-optical atom laser.