Quantum dynamics and decoherence in coherently driven one-dimensional double-well system

We numerically study influence of a polychromatic perturbation on wave acket dynamics in one-dimensional double-well potential. It is found that time-dependence of the tunneling probability shows two kinds of the motion typically, coherent oscillation and irregular fluctuation, depending on the perturbation parameters. The coherent motion changes the irregular one as the increase of the strength and/or the number of frequency components of the perturbation. We discuss a relation between our model and decoherence in comparing with the result under stochastic perturbation. Furthermore we compare the quantum fluctuation, tunneling in the quantum dynamics with ones in the semiquantal dynamics.