Resonant, elliptical-polarization control of microwave ionization of hydrogen atoms

For certain ranges of the principal quantum number n(0) much greater than 1 a few units wide, ionization of hydrogen atoms by a 9.904 GHz electric field is observed to be extremely sensitive to elliptical polarization. Classical 3D Monte Carlo calculations quantitatively reproduce the experimental data. Classical theory shows that the observed sensitivity to elliptical polarization is a resonant effect in this strongly driven quantal system. The resonant dynamics provides a mechanism for controlling the ionization.