Interactions in a Quantum Gas of Dysprosium Atoms

The subject of this thesis is the creation of a dipolar quantum gas of dysprosium atoms as well as the investigation of its two-body interactions. For this purpose we setup a new experimental apparatus which allows us to study dipolar many-body systems with ultra-cold bosonic as well as fermionic dysprosium atoms. In this work I present our developed cooling and trapping scheme to create a cold sample of dysprosium atoms based on a magneto-optical trap operating at the 626 nm transition and forced evaporative cooling in a crossed optical dipole trap. With our methods we can create Bose-Einstein condensates as well as degenerate Fermi gases. By comparing the experimentally obtained data with the prediction of theoretical calculations we show that for both bosonic isotopes the dipole-dipole interaction dominates the two-body interaction energy. Furthermore, we observe the effects of the complex atomic structure of dysprosium as a dense and correlated distribution of narrow Feshbach resonances. Despite many narrow resonances we also observe broad resonances which are caused by universal s-wave halo states. These resonances offer the possibility to tune the two-body interactions in dysprosium in a controlled way.