Ions and electrons interacting with ultracold atoms : novel approaches based on Rydberg excitations

Abstract

In this thesis, the interaction of ions and electrons with ultracold atoms was investigated at the example of Rubidium-87. Thereto, a Rydberg atom was excited in a dense ultracold cloud. Both the interaction of the ionic core of the Rydberg atom and the Rydberg electron itself with neighboring neutral atoms was studied. Two main achievements were reported: First, photo-association of hybrid Trilobite Rydberg molecules was demonstrated. This is a special type of homonuclear molecules with a large electric dipole moment, which is bound by the electron-atom interaction. Second, it was shown for the first time that the ion-atom interaction between the Rydberg ionic core and the neutral atom can be accessed experimentally. The ion-atom interaction was observed at submicrokelvin temperature, once the nearest neighbor spacing in BEC is small and the electron-atom interaction is suppressed.