Abstract
This thesis presents a simple theoretical model of a Feshbach resonance between two colliding ultracold atoms and experimental progress towards the observation of such a resonance in 85Rb. On the theoretical side, the inter-atomic scattering potential is approximated by a spherical square well potential. The potential supports a number of bounds states whose energy depends on the width and depth of the well. In the low energy limit, only s-wave scattering is present, and the associated scattering length for the process diverges if there is a bound state at the dissociation limit: this is the hallmark of a Feshbach resonance. The model also shows that the Feshbach resonance can be shifted to higher scattering energies by adjusting the well depth, indicating the presence of a quasi-bound state above the dissociation limit. On the the experimental side, a crossed dipole trap has been developed and used to trap ultracold rubidium atoms. The performance of the trap is characterized, and the thesis describes work towards upgrading it for an experiment to observe a Feshbach resonance in the F= 2, mF=-2 hyperfine ground state of 85Rb.
Isabelle Lee
PhD Student
2nd year PhD student at USC, interested in Emergence, Interpretability, and Reasoning.