Dynamics of quantum discord in photonic crystals

We study the system-reservoir dynamics of quantum correlations in the decoherence phenomenon within a two-qubit composite system interacting with a common photonic band-gap (PBG) environment. We compare the dynamics of entanglement with that of quantum discord. By analytical and numerical analyses we find that, the quantum discord can maintain a constant value in the long-time limit even when entanglement suddenly disappears. We also show that the detuning conditions play a crucial role in controlling quantum correlations of the two-qubit system. In PBG environment, the stationary quantum discord can be attained in well-controlled conditions. Our results have lots of potential applications to quantum information processing in nanostructured materials.