Delocalization induced by low-frequency driving in disordered tight-binding lattices

We study the localization properties of disordered one-dimensional tight-binding lattices driven by ac fields. The localization length of the electrons increases when the frequency of the driving field is smaller than the bandwidth. We show that there is an optimal value of the amplitude of the driving field for which the localization length of the system is maximal. This maximum localization length increases with the inverse of the driving frequency.