Exploring a metal-insulator transition with ultracold atoms in standing light waves?

We suggest the possibility to realize an optical quasicrystal with ultracold atoms in far-detuned, bichromatic standing light waves. If the optical potentials created by the individual light waves have sufficiently different strength, one obtains an atom-optical realization of Harper's model. This model exhibits a metal-insulator transition at a certain value of the site-to-site hopping integral. Since this hopping integral is effectively renormalized by an additional oscillating force, one can switch from the regime of extended states to the regime of localized states by varying the amplitude of that force.