  We consider two identical and non-interacting harmonic oscillators coupled to
either two independent bosonic baths or to a common bosonic bath. Under the
only assumption of weak coupling, we analyze in details the non-Markovian short
time-scale evolution of intensity correlations, entanglement and quantum
discord for initial two-mode squeezed-thermal vacuum states. In the independent
reservoirs case we observe the detrimental effect of the environment for all
these quantities and we establish a hierarchy for their robustness against the
environmental noise. In the common reservoir case, for initial uncorrelated
states, we find that only quantum discord can be created via interaction with
the bath, while entanglement and sub shot noise intensity correlations remain
absent.
