Spectral estimates of dynamically-defined and amenable operator families

Fuente: arXiv
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Autores principales: Beckus, Siegfried, Takase, Alberto
Formato: Preprint
Publicado: 2021
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author Beckus, Siegfried
Takase, Alberto
author_facet Beckus, Siegfried
Takase, Alberto
contents We consider kernel operators defined by a dynamical system. The Hausdorff distance of spectra is estimated by the Hausdorff distance of subsystems. We prove that the spectrum map is $ \frac{1}{2} $-Hölder continuous provided the group action and kernel are Lipschitz continuous and the group has strict polynomial growth. Also, we prove that the continuity can be improved resulting in the spectrum map being Lipschitz continuous provided the kernel is instead locally-constant. This complements a 1990 result by J.~Avron; P.H.M.v.~Mouche; B.~Simon establishing that one-dimensional discrete quasiperiodic Schrödinger operators with Lipschitz continuous potentials, e.g., the Almost Mathieu Operator, exhibit spectral $ \frac{1}{2} $-Hölder continuity. Also, this complements a 2019 result by S.~Beckus; J.~Bellissard; H.~Cornean establishing that $ d $-dimensional discrete subshift Schrödinger operators with locally-constant potentials, e.g., the Fibonacci Hamiltonian, exhibit spectral Lipschitz continuity. Our work exposes the connection between the past two results, and the group, e.g., the Heisenberg group, needs not be the integer lattice nor abelian.
format Preprint
id arxiv_https___arxiv_org_abs_2110_05763
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Spectral estimates of dynamically-defined and amenable operator families
Beckus, Siegfried
Takase, Alberto
Spectral Theory
Mathematical Physics
We consider kernel operators defined by a dynamical system. The Hausdorff distance of spectra is estimated by the Hausdorff distance of subsystems. We prove that the spectrum map is $ \frac{1}{2} $-Hölder continuous provided the group action and kernel are Lipschitz continuous and the group has strict polynomial growth. Also, we prove that the continuity can be improved resulting in the spectrum map being Lipschitz continuous provided the kernel is instead locally-constant. This complements a 1990 result by J.~Avron; P.H.M.v.~Mouche; B.~Simon establishing that one-dimensional discrete quasiperiodic Schrödinger operators with Lipschitz continuous potentials, e.g., the Almost Mathieu Operator, exhibit spectral $ \frac{1}{2} $-Hölder continuity. Also, this complements a 2019 result by S.~Beckus; J.~Bellissard; H.~Cornean establishing that $ d $-dimensional discrete subshift Schrödinger operators with locally-constant potentials, e.g., the Fibonacci Hamiltonian, exhibit spectral Lipschitz continuity. Our work exposes the connection between the past two results, and the group, e.g., the Heisenberg group, needs not be the integer lattice nor abelian.
title Spectral estimates of dynamically-defined and amenable operator families
topic Spectral Theory
Mathematical Physics
url https://arxiv.org/abs/2110.05763