Mario Collura, Pasquale Calabrese
We study the out-of-equilibrium time evolution after a local quench connecting two anisotropic spin-1/2 XXZ Heisenberg open chains via an impurity bond. The dynamics is obtained by means of the adaptive time-dependent density-matrix renormalization group. We show that the entanglement entropies (Von Neumann and R\'enyi), in the presence of a weakened bond depend on the sign of the bulk interaction. For attractive interaction (\Delta< 0), the defect turns out to be irrelevant and the evolution is asymptotically equivalent to the one without defect obtained by conformal field theory. For repulsive interaction (\Delta>0), the defect is relevant and the entanglement saturates to a finite value. This out-of-equilibrium behavior generalizes the findings for the ground-state entanglement of the model.
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http://arxiv.org/abs/1302.4274
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