  A simple model of a two-mode non-resonant parametric amplifier is studied
with special regard to non-classical features such as revivals and squeezing.
The methods used apply for an arbitrary pump parameter. Detailed analytical and
explicit expressions are given when the coupling of the two modes has an
harmonic time-dependence. Despite its simplicity the model exhibits a very
broad range of intricate physical effects. We show that quantum revivals are
possible for a broad continuous range of physical parameters in the case of
initial Fock states. For coherent states we find that such revivals are
possible only for certain discrete rational number combinations of the ratio of
frequency detuning and pump parameters. Correlation effects are shown to be
very sensitive to the initial state of the system.
