Berlin 2024 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Many-Body Systems: Equilibration, Chaos, and Localization (joint session DY/TT)

TT 29.5: Vortrag

Dienstag, 19. März 2024, 10:30–10:45, A 151

Prethermalization in an Interacting Flat Band System — •Mirko Daumann and Thomas Dahm — Universität Bielefeld, Fakultät für Physik, Postfach 100131, D-33501 Bielefeld

Studying the influence of a weakly perturbed flat band on transport of interacting particles reveals anomalous diffusion and prethermalization. For very weak perturbations transport is getting slower than regular diffusion because of repulsive particle-particle interaction. The effect can be understood by a canonical transformation of dispersive and flat band eigenstates into a basis of light and heavy quasiparticles which are trapping each other. They are subjected to orbital conservation laws what enables a treatment of the phenomenon in terms of the Born-Oppenheimer approximation and allows an illustration in a familiar physical picture analogous to electrons and nuclei. This approach furthermore sheds light on the thermalization process in such a system in general.

Methodology: Transport properties are calculated by simulating the broadening of initially localized wave packets of spinless fermions in a quasi one-dimensional Hubbard model with three-orbital diamond structure. Initial states are constructed in the framework of dynamical quantum typicality. Time evolution is performed by either the Lanczos algorithm or full diagonalization if possible.

Keywords: Flat Band; Prethermalization; Localization; Thermalization; Born-Oppenheimer approximation