Measurement of interaction energy near a Feshbach resonance in a 6Li Fermi gas

Abstract

We investigate the strongly interacting regime in an optically trapped ${}^6$Li Fermi mixture near a Feshbach resonance. The resonance is found at $800(40)$G in good agreement with theory. Anisotropic expansion of the gas is interpreted by collisional hydrodynamics. We observe an unexpected and large shift ($80$G) between the resonance peak and both the maximum of atom loss and the change of sign of the interaction energy.

4 pages, 4 figures