Cantor Spectrum for Schr\"odinger Operators with Potentials arising from Generalized Skew-shifts
Abstract
We consider continuous -cocycles over a strictly ergodic homeomorphism which fibers over an almost periodic dynamical system (generalized skew-shifts). We prove that any cocycle which is not uniformly hyperbolic can be approximated by one which is conjugate to an -cocycle. Using this, we show that if a cocycle's homotopy class does not display a certain obstruction to uniform hyperbolicity, then it can be -perturbed to become uniformly hyperbolic. For cocycles arising from Schr\"odinger operators, the obstruction vanishes and we conclude that uniform hyperbolicity is dense, which implies that for a generic continuous potential, the spectrum of the corresponding Schr\"odinger operator is a Cantor set.
Keywords
Cite
@article{arxiv.0709.2667,
title = {Cantor Spectrum for Schr\"odinger Operators with Potentials arising from Generalized Skew-shifts},
author = {Artur Avila and Jairo Bochi and David Damanik},
journal= {arXiv preprint arXiv:0709.2667},
year = {2009}
}
Comments
Final version. To appear in Duke Mathematical Journal