Title:	Influence of matrix structures in spin systems
Authors:	Lamann, Mats H.
Thesis advisor:	Prof. Dr. Jochen Gemmer
Thesis referee:	Prof. Dr. Robin Steinigeweg
Abstract:	Within this thesis the effect of structures of quantum systems and their impact on the dynamics of these systems are investigated. At first, the focus will be on the properties of elements of specific observables in the energy eigenbasis. In this approach, a framework already exists with the Eigenstate Thermalization Hypothesis (ETH), which makes certain assumptions about those elements. The assumptions were investigated within the work for different spin-$1/2$ models. These results have been published in Ref.\ P1 and contradict assumptions made by ETH in a strict sense. Furthermore, the results from Ref.\ P2 will be presented, which investigates a new type of perturbation theory based on similar assumptions to those of ETH. It is shown that the perturbation theory can yield good results in spite of non-satisfied assumptions, but those cases can either be explained otherwise and/or it is questionable whether these results are transferable to mesoscopic systems. Cases in which all assumptions are strictly fulfilled were not found. In addition, further investigations were carried out based on the fact that autocorrelation functions can be described as 1-dimensional transport dynamics. Thereby possibilities were investigated, which allow a substantial reduction of the complicity of the transport.
URL:	https://doi.org/10.48693/446 https://osnadocs.ub.uni-osnabrueck.de/handle/ds-2024011610217
Subject Keywords:	Eigenstate Thermalization Hypothesis; Mori Chain; Lanczos Method
Issue Date:	16-Jan-2024
License name:	Attribution 3.0 Germany
License url:	http://creativecommons.org/licenses/by/3.0/de/
Type of publication:	Dissertation oder Habilitation [doctoralThesis]
Appears in Collections:	FB06 - E-Dissertationen

This item is licensed under a Creative Commons License