Effective Rb-Rb inter-atomic potential from ultracold Bose-gas collisions

Scattering phase shifts obtained from 87Rb Bose-gas collision experiments are used to reconstruct effective potentials resulting, self-consistently, in the same scattering events observed in the experiments at a particular energy. We have found that the interaction strength close to the origin suddenly changes from repulsion to attraction when the collision energy crosses, from below, the l = 2 shape resonance position at E ∼ 275 μK. This observation may be utilized in outlining future Bose-gas collision experiments