Elastic and inelastic dipolar scattering

Abstract

Quantum gases offer experimentalists and theorists a versatile and controllable platform to study quantum physics. From simple individual atoms, physicists can build complex systems that show new phenomena. Most of those emerging phenomena arise from interactions. The strength of the interactions is an essential parameter for a quantum gas experiment. If the interactions are too weak or lead to rapid losses, the experiment cannot succeed.

The dipolar interaction has many features making it attractive in the physicist toolbox. Molecules usually feature strong dipolar interactions, but we use dysprosium which is still the most magnetic atom and is easier to manipulate than molecules. However, the magnetic interaction between dysprosium atoms still needs to be stronger to be useful. Moreover, dipolar interaction can lead to detrimental losses called dipolar relaxation. We developed and demonstrated two new experiments to address both issues.

The first one utilizes the repulsive character of the side-by-side dipolar interaction to shield the atoms and prevent dipolar relaxation. The second one demonstrates a new technique to place the atoms closer than ever in a cold-atom experiment in a controlled way. We create a novel bilayer system with dysprosium and observe a much stronger dipolar interaction. This thesis also gives detailed derivations to understand dipolar scattering in 3D and 2D geometries.