Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 24: Poster II

Q 24.34: Poster

Tuesday, March 12, 2024, 17:00–19:00, KG I Foyer

Quantized pumping in optical lattices: interactions and edge modes — •Giacomo Bisson, Zijie Zhu, Konrad Viebahn, Samuel Jele, Marius Gächter, Anne-Sophie Walter, Joaquin Minguzzi, Stephan Roschinski, Kilian Sandholzer, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich

Understanding the underlying geometric properties of wave functions in topological quantum systems is essential in explaining phenomena such as the quantized Hall effect and Thouless pumps. However, interparticle interactions can affect the topology of a system. In our work, we study topological Thouless pumps via an experimental realization using optical lattices where the Hubbard interaction can be tuned. We observe regimes with robust pumping, as well as an interaction-induced breakdown. The pump shows robustness against weak interactions, both repulsive and attractive. Strongly attractive interactions enable quantized transport through the formation of fermion pairs. Conversely, strong repulsive interaction impairs topological pumping, necessitating pump trajectory modifications to restore it. Furthermore, we explore pump trajectories that are trivial in the non-interacting case and non-trivial in the interacting case resulting in an interaction-induced charge pump. Additionally, we study the transport properties of gapless edge modes in a harmonically confined topological pump. When ultracold fermionic atoms reach a critical slope of the confining potential, quantized Hall drifts reverse, indicating a topological boundary. This reversal corresponds to a band transfer between bands with Chern numbers C = +1 and C = -1 through a gapless edge mode.

Keywords: topology; strongly correlated quantum matter; synthetic gauge fields; fermi-hubbard model