J. Bourgain, S. Jitomirskaya
Nonperturbative absolutely continuous spectrum for 1D quasiperiodic operators.
(458K, ps)

ABSTRACT.  We prove that 1D discrete Schroedinger operators with potential of the form $\lambda f(\omega n +\theta),$ where $f$ is a 1-periodic analytic function, have purely absolutely continuous spectrum for $\lambda < 
\lambda(f),$ Diophantine $\omega$ and a.e. $\theta.$