  We analyze the response of a complex quantum-mechanical system (e. g., a
quantum dot) to a time-dependent perturbation. Assuming the dot energy spectrum
and the perturbation to be described by the Gaussian Orthogonal Ensemble of
random matrices we find the quantum corrections to the energy absorption rate
as a function of dephasing time. If the perturbation is a sum of d harmonics
with incommensurate frequencies, the quantum corrections behave similarly to
those of conductivity for the d-dimensional Anderson model of the orthogonal
symmetry class. For periodic perturbations, the leading quantum corrections are
generically absent as in the systems of the unitary symmetry class. Exceptions
are the harmonic perturbation and all other periodic perturbations that obey
the generalized time-reversal condition (with an arbitrary time shift). Such
cases fall into the quasi-1d orthogonal universality class.
