Bichromatic drive prediction of a giant resonance

Two-frequency irradiation of a two-level atom was proposed by Pomeau et al. (1986). As compared with one-frequency irradiation, a rapid decay of correlations, indicative of true quantum chaos, was observed. However, for the particular choice of parameters in the paper by Pomeau et al. (1986), Badii and Meier (1987) were able to demonstrate that the response is not chaotic, but quasi-periodic, albeit on a very long time 

The mechanisms (a) and (c) are discussed in more detail below. Theoretical and experimental results are currently available that confirm the existence and validity of the two resonance switching mechanisms. Mechanism (b) has not yet been tested, either theoretically or experimentally. Of course, by simultaneously changing two or all three parameters, any combination of (a) - (c) can be used to define a generalized switch. Depending on how fast the field parameters can be changed experimentally, the three fundamental switches (a) - (c) and their generalizations are potentially very fast and may find some interesting technical applications. 

The three switches defined above rest on the mechanism of interspersed resonances, which was first suggested theoretically by Howard (1991). In the following we demonstrate the action of such a switch in the case of bichromatically driven hydrogen Rydberg atoms. It results in the prediction of a new kind of ionization peak in the microwave ionization of hydrogen Rydberg atoms. Recently performed experiments indicate that the effect actually exists. 

The prediction of the giant resonance in microwave ionization starts from the one-dimensional Hamiltonian 

We consider now the case of an arbitrarily chosen frequency ui. For ionization to occur it is necessary that the interspersed resoance overlaps with both the I2 72.2 and the I w 57.3 resonances. The position of the interspersed resonance is given by 7/ = 187.35/ /. With (7.3.2) we obtain the following two conditions for resoance overlap  

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