Non-zero quantum discord at finite temperature

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.