We investigate theoretically the quantum discord dynamics of a two-qubit composite system subject to a common finite-temperature reservoir by solving the Born-Markovian master equation analytically.The ultimate quantum discord,however,exhibits a relatively high stable value associated with the reservoir temperature despite the permanent disappearance of entanglement simultaneously.Further analysis shows that the unique characteristic depends strongly on the off-diagonal non-zero elements of the density matrix.Our result manifests the greater robustness of quantum discord compared with entanglement,which may be helpful in quantum-information technologies.
Starting from a rudimentary quantum-networks model that consists of two two-level confined atoms locating respectively in spatially-separated cavities coupled by fiber,we investigate the complex entanglement characteristics of the composite system analytically under the maximally initial entangled state that generates two excitations simultaneously during the temporal-evolution process.Our calculation clearly shows that,through mediating the atom-cavity coupling strength and photon-photon hopping rate appropriately,the entanglement dynamics displays some distinctive temporal properties differing from those obtained in one-excitation space,characterized partially by these newly quantum phenomena termed as entanglement sudden death and recurrence.Effectively,within the framework of two excitations,we suggest the purposeful manipulations of atomic entanglement communication for quantum networks.
