  Several examples are known where quantum gravity effects resolve the
classical big bang singularity by a bounce. The most detailed analysis has
probably occurred for loop quantum cosmology of isotropic models sourced by a
free, massless scalar. Once a bounce has been realized under fairly general
conditions, the central questions are how strongly quantum it behaves, what
influence quantum effects can have on its appearance, and what quantum
space-time beyond the bounce may look like. This, then, has to be taken into
account for effective equations which describe the evolution properly and can
be used for further phenomenological investigations. Here, we provide the first
analysis with interacting matter with new effective equations valid for weak
self-interactions or small masses. They differ from the free scalar equations
by crucial terms and have an important influence on the bounce and the
space-time around it. Especially the role of squeezed states, which have often
been overlooked in this context, is highlighted. The presence of a bounce is
proven for uncorrelated states, but as squeezing is a dynamical property and
may change in time, further work is required for a general conclusion.
