title: Extreme tunability of interactions in a 7Li Bose-Einstein condensate.
abstract: We use a Feshbach resonance to tune the scattering length a of a Bose-Einstein condensate of 7Li in the |F=1,mF=1> state. Using the spatial extent of the trapped condensate, we extract a over a range spanning 7 decades from small attractive interactions to extremely strong repulsive interactions. The shallow zero crossing in the wing of the Feshbach resonance enables the determination of a as small as 0.01 Bohr radii. Evidence of the weak anisotropic magnetic dipole interaction is obtained by comparison with different trap geometries for small a.
authors.affiliation: Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Pollack
authors.forename: D
authors.initials: D
authors.lastname: Dries
authors.forename: M
authors.initials: M
authors.lastname: Junker
authors.forename: Y P
authors.initials: YP
authors.lastname: Chen
authors.forename: T A
authors.initials: TA
authors.lastname: Corcovilos
authors.forename: R G
authors.initials: RG
authors.lastname: Hulet