Abstract:

The angulon quasiparticle allows for the description of a rotating impurity in the many-body environment. For example, they are formed from molecules in superfluid helium nanodroplets. Theoretical research also predicts that angulon can be formed out of other impurities with angular momenta, such as molecular ions in ultracold gases or in lead halide perovskites.

In our study, we focus on the formation and fate of the angulon quasiparticle in the crossover from few- to many-body physics. To this end, we investigate the system of a molecular quantum rotor in a two-dimensional Bose gas. We show that the system starts to feature angulon characteristics when the size of the bosonic cloud is large enough to screen the rotor. More importantly, we demonstrate the departure from the angulon picture for large system sizes or large angular momenta where the properties of the system are determined by collective excitations of the Bose gas. We will briefly discuss the outlook for further research focused on the emergence of collective excitations, such as solitons and vortices in the system after rapid impurity rotation. The talk will be based on arXiv:2407.06046.