München 2004 – scientific programme
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Q: Quantenoptik und Photonik
Q 44: Gruppenberichte Quantengase
Q 44.1: Group Report
Thursday, March 25, 2004, 16:30–17:00, HS 225
Realization of an Atom Laser based on Bose-Einstein condensates in magneti field insensitive states — •Giovanni Cennini, Gunnar Ritt, Carsten Geckeler, and Martin Weitz — Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen Germany.
A novel type of atom laser is realized by all optical techniques [1]. Our experiment is based on a Bose-Einstein condensate (BEC) of atoms generated by direct evaporative cooling of atoms in a single beam optical dipole trap. The atoms are in mF=0 Zeeman state, making this atom laser insensitive to stray magnetic fields.
In our apparatus, cold rubidium atoms are initially prepared in a magneto-optical trap and then transferred to a CO2-laser optical dipole trap. Such optical traps offer a state-independent confinement, allowing for studies of atomic systems which cannot be stored in magnetic traps, such as multiple spin-states. Evaporation to a BEC is achieved by continuously lowering the trapping potential depth. This generates a spinor condensate with 1.2×104 atoms distributed among the different Zeeman states of the hyperfine ground state F=1. When a moderate magnetic gradient is applied, the atoms condense into a field insensitive mF=0 Zeeman state alone. Once the degenerate regime is achieved, the trapping potential is smoothly lowered until gravity couples out condensed atoms. The stability of the generated coherent, monoenergetic beam is limited only by trapping laser intensity fluctuations.