Quantum correlations in the dimerized spin chain at zero and finite temperatures

By using the method of exact diagonalization, we investigate the quantum correlation measured by quantum discord of the dimerized spin chain at both zero and finite temperatures. The results disclose that the quantum discord is robust at any finite parameter alpha and temperature T, in contrast to entanglement which shows a sudden death when the parameter alpha or the temperature T reaches a critical point. At finite temperature, it is interesting to find that the quantum discord QD (2i-1, 2i) can increase with temperature T no matter if the entanglement EoF (2i-1, 2i) exists or not. The research on the relation between the quantum discord and the quantum phase transition in the dimerized spin chain indicates that the transition can be characterized by the first derivation of the quantum discord at zero and low temperatures.