  In the framework of the theory of open systems based on completely positive
quantum dynamical semigroups, we give a description of continuous variable
quantum entanglement and quantum discord for a system consisting of two
non-interacting non-resonant bosonic modes embedded in a thermal environment.
We study the time evolution of logarithmic negativity, which characterizes the
degree of entanglement, and show that in the case of an entangled initial
squeezed thermal state, entanglement suppression takes place for all
temperatures of the environment, including zero temperature. We analyze the
time evolution of the Gaussian quantum discord, which is a measure of all
quantum correlations in the bipartite state, including entanglement, and show
that discord decays asymptotically in time under the effect of the thermal
bath. We describe also the time evolution of classical correlations and quantum
mutual information, which measures the total correlations of the quantum
system.
