We study the dynamics of quantum and classical correlations in the presence of nondissipative decoherence. We discover a class of initial states for which the quantum correlations, quantified by the quantum discord, are not destroyed by decoherence for times $t<\overline{t}$. In this initial time interval classical correlations decay. For $t>\overline{t}$, on the other hand, classical correlations do not change in time and only quantum correlations are lost due to the interaction with the environment. Therefore, at the transition time $\overline{t}$ the open system dynamics exhibits a sudden transition from classical to quantum decoherence regime.

• Received 3 December 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.200401