Macroscopic States of Dipolar Quantum Gases

In this thesis, we investigate macroscopic many-body quantum states of ultracold bosons with dipolar interaction both experimentally and theoretically. We thereby focus on a novel state of matter, the dipolar quantum droplet, that exists due to the interplay of attractive binary interactions and repulsive quantum fluctuations. In this context, we predict groundstates with multiple droplets. These are promising candidates for the realization of a supersolid phase merging both superfluidity and a density modulation, that resembles the solid phase. Furthermore, we extend our studies on single droplets and measure its collective excitations. We also investigate the immersion of a fermionic impurity to probe the bosonic quantum droplet and predict a novel kind of droplet for an inverted dipolar interaction. In addition, we study the superfluid properties of a Bose-Einstein condensate with dipolar interactions featuring an anisotropic excitation spectrum. Based on this effect, we measure an anisotropy of the critical velocity for the breakdown of superfluidity in the gas and predict the deformation of vortex cores and striped vortex lattices in rotating gases for our experimental parameters.