Trapped ions in a bath of ultracold atoms

In this thesis we describe an experimental setup designed for preparing an ultracold sample of ⁶Li atoms and overlap it with Yb⁺ ions that are trapped in a radiofrequency trap. Within this thesis, we focus on answering the following main research questions: 1) Can our system reach the quantum regime of interacting atoms and ions? 2) Is the ionic spin conserved when colliding with a spin-polarized atomic gas such that it can be used as a buffer-gas cooled qubit? 3) Can we expect to tune the atom-ion interaction in the ultracold regime by using Feshbach resonances? To address these questions, we characterize our system experimentally and simulate the behavior when entering the ultracold regime. We measure the spin dynamics of a single ionic spin when colliding with a cloud of ultracold atoms. Comparing our results to quantum-scattering calculations, we draw conclusions about the accessibility of Feshbach resonances for this particular combination of atoms and ions. Further, we perform spectroscopic measurements on different Yb⁺ isotopes. The investigated transitions will be helpful when entering the quantum regime, as they can be used for cooling and thermometry of the ions.