  We study dynamical properties of systems with many interacting
Fermi-particles under the influence of static imperfections. Main attention is
payed to the time dependence of the Shannon entropy of wave packets, and to the
fidelity of the dynamics. Our question is how the entropy and fidelity are
sensitive to the noise. In our study, we use both random matrix models with
two-body interaction and dynamical models of a quantum computation. Numerical
data are compared with analytical predictions.
