Topological Effects in Low-dimensional Quantum Gases

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Topological concepts have gained increasing importance in the description of physical phenomena. Prominent examples in condensed matter physics include the quantum Hall effect and the fascinating electronic properties of topological insulators. In the presence of interactions, many-body states with even more intriguing electronic properties have been predicted, which exhibit excitations with fractional charges and non-trivial statistics that are neither bosonic nor fermionic. Quantum simulations with ultracold atoms in optical lattices constitute a promising avenue for studying these non-trivial topological many-body systems. Experiments have achieved impressive results on the engineering and characterization of topological band structures. However, so far these studies were mostly limited to the non-interacting regime. Extending the experimental protocols to the interacting regime requires the combined effort of theory and experiments. Within this Research Unit we pursue the following two main goals: the preparation of low-entropy fractional Chern insulators and the development of experimental observables to study the exotic properties of topological many-body states. In order to achieve these challenging goals, we employ the following strategy: (i) Continue ongoing experimental efforts for realizing long-lived topological systems in the weakly-interacting regime, which have been found to be limited by interaction-induced as well as technical heating. In this context we will also work towards generating novel topological systems, which have no analog in static systems, study the interplay between topology and disorder, investigate topological proximity effects in bilayer systems and develop alternative experimental techniques to realize topological systems. (ii) Design and construct a quantum gas microscope, which will provide access to novel experimental observables and techniques for preparing and studying topological many-body systems via local observables and interfaces. Moreover, we will collaborate with the theory teams of this Research Unit in order to identify optical lattice settings that are suited to directly study anyonic models and extend current platforms to investigate dynamical gauge fields.