Quasi Many-Body Localization in Translation Invariant Systems

We examine localization phenomena associated with generic, high entropy, states of a translation invariant, one-dimensional spin ladder. At intermediate time scales, we find slow growth of entanglement entropy consistent with the known phenomenology of many-body localization in disordered, interacting systems. At longer times, however, anomalous diffusion sets in, leading to full spin polarization decay on a time-scale exponential in system size. We identify a single length scale which parametrically controls both the eventual spin transport times and the divergence of the susceptibility to spin glass ordering. We dub this pre-thermal dynamical behavior, quasi many-body localization.