Floquet Dynamics Research Articles

Multistate non-Hermitian Floquet dynamics in short laser pulses

A time-dependent non-Hermitian close-coupling method is developed for describing the interplay of decaying atomic dressed states in short laser pulses. This interplay accounts for a variety of phenomena. It is shown, in particular, that the probability that the atom is excited off-resonance is modulated by Stueckelberg oscillations, that the ionization yield may be reduced by dynamical coupling with a resonant and rapidly decaying dressed state, and that adiabatic stabilization of circular states subsists down to very short pulse durations.

Dissociation dynamics of a model diatomic species in an intense pulsed laser field: a time dependent Fourier grid Hamiltonian approach

A time dependent Fourier grid Hamiltonian (TDFGH) method is employed to model the quantum dynamics of a pulsed Morse oscillator. The Morse oscillator is chosen to represent the bound states of the LiH molecule. The dissociation is seen to be characterized by a definite induction period and a threshold of peak laser intensity only beyond which noticeable dissociation takes place. The positive features of the present method are pointed out. Floquet state dynamics is invoked to explain some of the observed features.

Adiabatic processes in the ionization of highly excited hydrogen atoms

Adiabatic and non-adiabatic processes in the dynamics of periodically driven quantum systems are studied employing the Floquet picture of quantum mechanics. The validity ofN-niveau approximations in the Floquet theory is investigated. A method is described which allows the separation of fast (periodic) and slow (parametric) time-dependence and which yields a transparent description of the dynamical Landau-Zener mechanism. Using the model of surface-state electrons it is demonstrated that adiabaticity is decisive for the description of ionization experiments on highly excited hydrogen atoms; furthermore, an ionization mechanism based on the sudden onset of Landau-Zener transitions is proposed and shown to yield values for the ionization threshold which are in good agreement with experimental data. The connection to classical mechanics is considered by establishing the semiclassical limit of Floquet dynamics.