Fabian Heidrich-Meisner (University of Göttingen, Germany): Topological charge pumping with ultracold atomic gases

Clarifying the evolution of topological states of matter with interactions is a core goal of condensed matter theory, ranging from the stability of topological insulators to the emergent regime of topological quantum matter. Ultracold quantum gases in optical lattices provide unique opportunities to realize topological band-structures, yet face challenges concerning the loading of the bulk and the stability against heating in the interacting case inherent to Floquet engineering scheme. Topological charge pumps are conceptionally related to integer quantum Hall effects via dimensional reduction, with a different physical manifestation via the quantized charge. Their realization, notably, does not require fast driving and relies on established experimental loading schemes and therefore, this system provides unique opportunities to investigate the effect of interactions. I will report on three main results. First, we investigated the stability of charge pumping in the bosonic systems. Second, we characterized the breakdown of quantized pumping due to the addition of quenched disorder. Finally, we turn to interacting fermions and show that interactions can change the pumped charge per cycle from the value obtained for noninteracting systems.