Abstract
Many-body localization is characterized by a slow logarithmic growth of the entanglement entropy after a global quantum quench while the local memory of an initial density imbalance remains at infinite time. We investigate how much the proximity of a many-body localized phase can influence the dynamics in the delocalized ergodic regime where thermalization is expected. Using an exact Krylov space technique, the out-of-equilibrium dynamics of the random-field Heisenberg chain is studied up to sites, starting from an initially unentangled high-energy product state. Within most of the delocalized phase, we find a sub-ballistic entanglement growth with a disorder-dependent exponent , in contrast with the pure ballistic growth of clean systems. At the same time, anomalous relaxation is also observed for the spin imbalance with a continuously varying disorder-dependent exponent , vanishing at the transition. This provides a clear experimental signature for detecting this nonconventional regime.
- Received 30 November 2015
DOI:https://doi.org/10.1103/PhysRevB.93.060201
©2016 American Physical Society