Binding energy of hydrogenic impurities in quantum dots under intense laser radiation.

We calculate the binding energy of on- and off-center hydrogenic impurities in a parabolic quantum dot subjected to an intense high-frequency laser field. An exactly solvable model that replaces the actual Coulomb interaction with the donor by a non-local separable potential is introduced for calculating the binding energy. The separable potential allows us to solve the problem exactly and all calculations are carried out analytically. The action of the laser irradiation results in dressed Coulomb and confinement potentials. At low laser intensity the binding energy is found to decrease when the impurity is shifted away from the origin. At high laser intensity and strong confinement the opposite behavior is observed. We propose a simple one-dimensional model that explains the observed crossover.