Adiabatens\"atze mit und ohne Spektrall\"uckenbedingung

TL;DR

This paper generalizes various adiabatic theorems to non-unitary evolutions in Banach spaces, covering cases with and without spectral gap conditions, and extends higher order theorems, broadening their applicability beyond previous results.

Contribution

It introduces more general adiabatic theorems for non-unitary evolutions in Banach spaces, including cases without spectral gaps and higher order versions, surpassing earlier theorems in scope.

Findings

Theorems with uniform gap condition are proven.

Theorems with non-uniform gap condition are established.

Adiabatic theorems without gap condition are developed.

Abstract

In this work we generalize some of the previously known adiabatic theorems to situations with non-unitary evolutions in Banach spaces. We prove adiabatic theorems with uniform gap condition (generalizing a theorem of Abou Salem), adiabatic theorems with non-uniform gap condition (generalizing a theorem of Kato) and qualitative as well as quantitative adiabatic theorems without gap condition (generalizing theorems of Avron and Elgart, and Teufel). Additionally, we give a generalized version of an adiabatic theorem of higher order due to Nenciu. In all these adiabatic theorems the considered spectral values need not lie on the imaginary axis and in the adiabatic theorems with spectral gap condition and the adiabatic theorem of higher order compact subsets of the spectrum are sufficient (in particular, these subsets need not consist of eigenvalues). We explore the strength of the presented adiabatic theorems in numerous examples. In particular, we show that the theorems of the present work are more general than the previously known theorems. This work was finished in October 2010 and handed in as a diploma thesis at the mathematics department of the University of Stuttgart. The more recent results of Avron, Fraas, Graf und Grech which appeared in the meantime (in June 2011) are therefore not taken into consideration here. We point out, however, that the theorems of the present work are more general than the corresponding theorems of Avron, Fraas, Graf und Grech - with the exception of the adiabatic theorem of higher order which is in no logical relation to the adiabatic theorem of higher order of Avron, Fraas, Graf and Grech. We are about to gather the most important theorems of the present work in an article and will upload it to arXiv soon.