Quasi Many-body Localization in Translation Invariant Systems
  It is typically assumed that disorder is essential to realize Anderson localization. Recently, a number of proposals have suggested that an interacting, translation invariant system can also exhibit localization. We examine these claims in the context of a one-dimensional spin ladder. At intermediate time scales, we find slow growth of entanglement entropy consistent with the phenomenology of many-body localization. However, at longer times, all finite wavelength spin polarizations decay in a finite time, independent of 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 long pre-thermal dynamical behavior, intermediate between full localization and diffusion, quasi-many body localization. 
N. Y. Yao, C. R. Laumann, J. I. Cirac, M. D. Lukin, J. E. Moore
cond-mat.dis-nn cond-mat.mes-hall cond-mat.stat-mech cond-mat.str-el quant-ph