Quantum and classical correlations in the anisotropic XY model with a single defect

We investigate the quantum and classical pairwise correlations in the one-dimensional anisotropic XY spin chain with a single defect. The rigorous analysis and numerical results reveal that the quantum discord and classical correlation in different quantum phases present different responses to the defect. In particular, we show that the non-local long-range quantum discord can be modified by a local control of the defect under ferromagnetic phase in such system.