Hannover 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

Q: Quantenoptik

Q 35: Quantengase 3: Gruppenberichte

Q 35.1: Gruppenbericht

Donnerstag, 27. März 2003, 11:00–11:30, E001

The Interacting Fermi Gas Near a Feshbach Resonance — •Kai Dieckmann, Claudiu A. Stan, Subhadeep Gupta, Zoran Hadzibabic, Christian H. Schunck, Martin W. Zwierlein und Wolfgang Ketterle — MIT, Cambridge, USA

Interactions between atoms can be strongly modified by tuning magnetic fields to Feshbach resonances where a molecular state has the same energy as the colliding atoms. For degenerate Fermi gases, such control over the interaction strength is crucial in the search for a superfluid phase transition. The character of such a transition varies with the interaction strength between the formation of Cooper pairs and condensation of diatomic molecules. A promising candidate for an experimental observation of fermionic superfluidity is ⁶Li for which a broad Feshbach resonance was predicted. We first discuss the possibilities of detecting the resonance by measuring properties depending on elastic collisions. We then present our results on the magnetic field dependence of inelastic decay of optically trapped fermionic ⁶Li gas of different spin compositions. The spin mixture of the two lowest hyperfine states showed two decay resonances at 550 G and 680 G, consistent with the predicted Feshbach resonances for elastic s-wave collisions. The data are interpreted considering the possibility of the formation weakly bound molecular states. The observed lifetimes of several hundred milliseconds are much longer than the expected time for Cooper pair formation and the phase transition to superfluidity. We finally discuss recent experimental progress towards this goal.