Dresden 2020 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 53: Poster: Quantum Dynamics, Chaos and Information; Many Body Systems

DY 53.1: Poster

Thursday, March 19, 2020, 15:00–18:00, P1A

Thermalization properties of a system with topological flat bands and impurities — •Stefan kleine Brüning and Thomas Dahm — Universität Bielefeld

Topological insulators posses edge states, which are gapless in contrast to the bulk states. Bi₂Se₃ is of particular interest, because of its relatively simple Hamiltonian and, most importantly, under the influence of a Zeeman field flat bands appear in thin stripes of this material[1].

Due to the zero group velocity of electrons in flat bands there is no thermalization for a localized initial state. The question arises how this non-thermalization behaviour and the localization changes in the presence of impurities. In this work we focus on disorder, which modifies the on-site energy of the material. The influence of this disorder is investigated numerically using time evolution. The observable of interest is a quantity which is related to the localization of the wavepacket. The behaviour of this observable under change of strength and number of impurities is compared to a situation without a flat band. To investigate the question of thermalization it is probed whether the eigenstate thermalization hypothesis holds. To do this we employ a method suggested by Steinigeweg et al.[2]. This method uses random state vectors and scaling behaviour to decide this matter.

[1] Paananen, T., & Dahm, T. Physical Review B, 87, 195447(2013).

[2] Steinigeweg, R., et al. Physical Review Letters, 112, 130403

   (2014).