  Chaotic instanton approach allows to describe analytically the influence of
the polychromatic perturbation on quantum properties of nonlinear systems.
Double well system with single, multiple and polychromatic kicked perturbation
is considered in the paper to compare quantitative analytical predictions with
the results of numerical calculations. Chaotic instantons are responsible for
the enhancement of tunneling far away from the exact (avoided) level crossings
in framework of the approach used. Time-independent averaged system is used for
regular approximation of the chaotic instanton solution in order to take into
account its contribution to the ground quasienergy doublet splitting. Formula
for the ground quasienergy levels' splitting was derived averaging trajectory
action in the stochastic layer in the framework of chaotic instanton approach.
Results of quasienergy spectrum numerical calculations and simulations for
tunneling dynamics are in good agreement with the obtained analytical
predictions.
