  A system of two coupled oscillators, each of them coupled to an independent
reservoir, is analysed. The analytical solution of the non-rotating wave master
equation is obtained in the high-temperature and weak coupling limits. No
thermal entanglement is found in the high-temperature limit. In the weak
coupling limit the system converges to an entangled non-equilibrium steady
state. A critical temperature for the appearance of quantum correlations is
found.
