Dynamical control of quantum tunneling due to ac Stark shift in an asymmetric coupled quantum dot

Dynamical suppression and enhancement of the quantum tunneling in an asymmetric coupled-quantum-dot structure is predicted to occur when a laser field drives a subband transition in one of the dots. The laser field induces the splitting and shift of the quasiresonant energy levels, i.e., ac Stark (or light) shift. As a result, the tunneling between the energy levels perturbed by the laser field and another level in the neighboring dot is strongly modified as the amplitude of the laser field is increased. Furthermore, it is shown that the amount of the ac Stark shift has an oscillatory behavior for large amplitudes of the laser field, which is not predicted from the conventional rotating-wave approximation for the matter-light interaction.