Role of interband and intraband current in laser interaction with bichromatic quasiperiodic crystals

We study the role of the inter- and intraband current in the laser interaction with the bichromatic quasiperiodic crystals. The interaction dynamics are simulated by solving the time-dependent Schrödinger equation in the $k$ space, and time evolution of the inter- and intraband current is obtained in a gauge-invariant form. We observed that for certain bichromatic potential ratios, the energy band structure of the "valence band" and the "conduction band" facilitates the interband transitions only at the center or at the edge of the Brillouin zone, which leads to a very interesting population transfer mechanism between the bands. The temporal profile of the inter- and intraband current gives a detailed account of the interaction. The higher-order harmonic generation is also studied for these bichromatic optical lattices, and the resultant harmonic yield is commented upon.