Control of common resonances in bichromatically driven hydrogen atoms

We report the first combined experimental-theoretical study to realize and control the behavior of common resonances in a periodically driven system. Experimental data for the ionization of H(n=51) atoms by a bichromatic (6 and 18 GHz), linearly polarized electric field pulse show how the relative field phase can be used to control the ionization. 1D classical calculations show how this results from the phase control of the pendulumlike, common resonances, whose existence requires, at lowest order, two commensurate frequencies.