Many solid-state NMR experiments exploit interference effects between time dependencies in the system Hamiltonian to design an effective time-independent Hamiltonian with the desired properties. Effective Hamiltonians can be designed such that they contain only selected parts of the full system Hamiltonian while all other parts are averaged to zero. A general theoretical description of such exp...

What happens to the QCD vacuum when a time-periodic circularly polarized laser field with sufficiently large intensity and frequency is applied? Based on Floquet formalism for periodically driven systems systematic low-energy effective theory of QCD, we show that above critical intensity, unstable against chiral soliton lattice pions; crystalline structure topological solitons spontaneously bre...

This work studies through the Floquet theory the stability of breathers generated by the anti-continuous limit. We used the Peyrard-Bishop model for DNA and two kinds of nonlinear potential: the Morse potential and a potential with a hump. The comparison of their stability was done in function of the coupling parameter. We also investigate the dynamic behaviour of the system in stable and unsta...

We consider the spectral form factor of random unitary matrices as well as of Floquet matrices of kicked tops, as given by the (squared moduli of) the traces tn = TrF n with the integer “time” n = 0,±1,±2, . . .. For a typical matrix F the time dependence of the form factor |tn| 2 looks erratic; only after a local time average over a suitably large time window ∆n does a systematic time dependen...

Parametric excitations are capable of stabilizing an unstable state, but they can also destabilize modes that are otherwise stable. Resonances come into play when the periodically forced base state undergoes a Hopf bifurcation from a limit cycle to a torus. A Floquet analysis of the basic state will identify such an event, but in order to characterize the resonances, one requires precise knowle...

We introduce a time-dependent perturbation method to calculate the number of created particles in a 1D cavity with an oscillating wall of the frequency Ω. This method makes it easy to find the dominant part of the solution which results from the parametric resonance. The maximal number of particles are created at the mode frequency Ω/2. Using the Floquet theory, we discuss the long-time behavio...

In ationary reheating is almost completely controlled by the Floquet indices, k. Using spectral theory we demonstrate that the stability bands (where k = 0) of the Mathieu and Lam e equations are destroyed even in Minkowski spacetime, leaving a fractal Cantor set or a measure zero set of stable modes in the cases where the in aton evolves in an almost-periodic or stochastic manner respectively....

Thermal convection in a fluid layer confined between two horizontal rigid boundaries has been studied with the help of the Floquet theory. The temperature distribution consists of a steady part and an oscillatory time-dependent part. Disturbances are assumed to be infinitesimal. Numerical results for the critical Rayleigh numbers and wave numbers are obtained. It is found that the disturbances ...