  We investigate the localization properties of a one-dimensional bichromatic
optical lattice in the tight binding regime, by discussing how exponentially
localized states emerge upon changing the degree of commensurability. We also
review the mapping onto the discrete Aubry-Andre' model, and provide evidences
on how the momentum distribution gets modified in the crossover from extended
to exponentially localized states. This analysis is relevant to the recent
experiment on Anderson localization of a noninteracting Bose-Einstein
condensate in a quasiperiodic optical lattice [G. Roati et al., Nature 453, 895
(2008)].
