Ultracold Fermi gases: from Bose-Einstein condensation of molecules to Cooper pairs

Full text: We will describe recent experiments aiming at studying superfluidity in ultra-cold Fermi gases. Because of the Pauli exclusion principle, cooling methods and analysis techniques developed for bosons must be modified for fermions. Thanks to a resonance phenomenon in ultra-cold collisions, it is possible to adjust the sign and magnitude of the effective interaction between trapped fermions and to enter into the strongly correlated regime. Taking advantage of this tunability of interactions, it has been possible to produce Bose-Einstein condensates (BEC) of molecules and to study some of their properties. We will then present data recorded in the crossover region between BEC of molecules and the BCS regime of fermions with weak attractive interaction. Finally a few perspectives for this work at the interface between atomic physics and condensed matter physics will be given. (author)