  We provide a detailed quantum treatment of the spectral characteristics and
of the dynamics of nondispersive two-electron wave packets along the
periodically driven, collinear frozen planet configuration of helium. These
highly correlated, long-lived wave packets arise as a quantum manifestation of
regular islands in a mixed classical phase space, which are induced by
nonlinear resonances between the external driving and the unperturbed dynamics
of the frozen-planet configuration. Particular emphasis is given to the
dependence of the ionization rates of the wave packet states on the driving
field parameters and on the quantum mechanical phase space resolution, preceded
by a comparison of 1D and 3D life times of the unperturbed frozen planet.
Furthermore, we study the effect of a superimposed static electric field
component, which, on the grounds of classical considerations, is expected to
stabilize the real 3D dynamics against large (and possibly ionizing) deviations
from collinearity.
