SAMOP 2023 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 52: Floquet Engineering and Topology

Q 52.6: Talk

Thursday, March 9, 2023, 16:00–16:15, E001

Probing boundaries in interacting topological systems — •Marius Gächter, Zijie Zhu, Anne-Sophie Walter, Konrad Viebahn, and Tilman Esslinger — ETH, Zurich, Switzerland

Boundaries between topologically distinct materials give rise to gapless edge modes whose robustness against perturbations makes them promising candidates for technological applications. Therefore, it is crucial to gain a better understanding of topological edge states, especially regarding their response to interparticle interactions. In our experiment, we study quantised bulk Hall drifts of interacting ultracold fermions in the presence of a harmonic confinement. We discovered that quantised drifts halt and reverse in the opposite direction at the topological boundary which emerges due to the harmonic confinement. In the absence of interactions this reflection can be understood as a transfer of atoms between bands with opposite Chern numbers C = +1 and C = -1 via a gapless edge mode, in agreement with the bulk-edge correspondence. Interestingly, this reflection can be used to study the edge in an interacting system since a non-zero repulsive Hubbard U leads to the emergence of an additional edge in the system, which is purely interaction-induced.