  We revisit the problem of the dynamics of quantum correlations in the exact
Tavis-Cummings model. We show that many of the dynamical features of quantum
discord attributed to dissipation are already present in the exact framework
and are due to the well known non-linearities in the model and to the choice of
initial conditions. Through a comprehensive analysis, supported by explicit
analytical calculations, we find that the dynamics of entanglement and quantum
discord are far from being trivial or intuitive. In this context, we find
states that are indistinguishable from the point of view of entanglement and
distinguishable from the point of view of quantum discord, states where the two
quantifiers give opposite information and states where they give roughly the
same information about correlations at a certain time. Depending on the initial
conditions, this model exhibits a fascinating range of phenomena that can be
used for experimental purposes such as: Robust states against change of
manifold or dissipation, tunable entanglement states and states with a
counterintuitive sudden birth as the number of photons increase. We furthermore
propose an experiment called quantum discord gates where discord is zero or
non-zero depending on the number of photons.
