Persistence of correlations in many-body localized spin chains*

We study the evolution and persistence of quantum and classical correlations between spatially separated sites in the disordered XXZ spin chain in its ergodic and many-body-localized phases using exact diagonalization and matrix product state simulations. We show that in the many-body-localized phase quantum entanglement survives in long-time limit, compared to exchange time, even though it is suppressed much stronger than the classical correlations. We study the residual entanglement and correlations as functions of the system size and on the disorder strength. Finally, we demonstrate the robustness of entanglement and correlations with respect to local dissipation in the bulk of the system. Thus, our studies suggest that the many-body localized phase is potentially useful for building quantum memory where distant qubits may be entangled.