Yao, N.Y.Laumann, C.R.Cirac, J.I.Lukin, MikhailMoore, J.E.2017-03-152016Yao, N. Y., C. R. Laumann, J. I. Cirac, M. D. Lukin, and J. E. Moore. 2016. “Quasi-Many-Body Localization in Translation-Invariant Systems.” Physical Review Letters 117 (24) (December 7). doi:10.1103/physrevlett.117.240601.0031-9007http://nrs.harvard.edu/urn-3:HUL.InstRepos:30779324It 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.en-USJournal Article2017-03-1510.1103/PhysRevLett.117.240601