Control of resonance states in crossed magnetic and laser fields

We analyze a two-dimensional model of electrons moving under the influence of an attractive zero-range potential, as well as external magnetic and circularly polarized laser fields. In order to determine complex energies of the resonance states of the electron, we apply the Green's function method. It is found that such resonances show a peculiar dependence on the laser-field intensity; i.e., although it increases, the lifetime of these resonance states increase. We show that this phenomenon can be attributed to quantum-mechanical vortices induced by the magnetic field and controlled by the strength of the laser field. In order to obtain more information about these vortices, the phase of wavefunctions and probability currents for these stable resonances are investigated.