English

Cantor Spectrum for Schr\"odinger Operators with Potentials arising from Generalized Skew-shifts

Dynamical Systems 2009-12-18 v2 Mathematical Physics math.MP Spectral Theory

Abstract

We consider continuous SL(2,R)SL(2,\mathbb{R})-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 SO(2,R)SO(2,\mathbb{R})-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 C0C^0-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