Hannover 2003 – wissenschaftliches Programm
Q 19.8: Vortrag
Dienstag, 25. März 2003, 15:45–16:00, F303
Evaporative Cooling in a CO2-Laser Optical Dipole Trap with Rubidium Atoms — •Giovanni Cennini, Gunnar Ritt, Carsten Geckeler, and Martin Weitz — Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany
Far detuned laser traps are attractive systems for both the study of quantum degeneracy and scalable quantum logic. We investigate the possibility of manipulating ultracold rubidium atoms collected in the focus of an extremely far detuned optical beam generated by a single frequency CO2-laser whose wavelength is near 10.6 µm. The dipole trap is loaded with rubidium atoms (87Rb) from a dark magneto-optical-trap. Due to the extreme detuning of the trapping laser, the photon scattering rate is below 10 minutes. Our new experimental apparatus gives the possibility of tight atomic confinement, as the mid-infrared trapping laser beam waist is only 30 µm. Therefore relatively high trap frequencies are obtained even in a single beam running configuration. The laser cooled sample yields an initial phase space density of about 10−3. Evaporative cooling has been carried out by reducing the trapping beam intensity. In initial experiments, we have cooled atoms to phase space density of 1/30 (with density n ≈ 1013 and temperature T ≈ 1 µK) in a simple dipole trap. We are planning to optimize parameters to allow for the observation of Bose-Einstein condensation in the trap. We will discuss recent experimental progress and future prospects.