Role of inter- and intraband current in laser interaction with bi-chromatic quasi-periodic crystals

We study the role of the inter- and intraband current in the laser interaction with the bi-chromatic quasi-periodic 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 bi-chromatic potential ratios, the energy band structure of the valence band' and the conduction band’ facilitate 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 (HHG) is also studied for these bi-chromatic optical lattices, and the resultant harmonic yield is commented upon.