Population trapping and excitation of a potassium atom in a frequency modulated field

Using the time-dependent multilevel approach developed by ourselves recently, we have, for the first time, calculated the stair step oscillations in the presence of intermediate modulation, and the square-wave population oscillation of the excited potassium atom in the presence of slow modulation. The numerical results are in good agreement with those of the experiments; a new way of realizing population trapping has been predicted, with a specially designed radio-frequency field.