Quasi-Many-Body Localization in Translation-Invariant Systems

December 12, 2016

Figure 1: Schematic of the one-dimensional spin-1/2 ladder.* [Reprinted by permission from APS.]

In spin ladder systems, a single characteristic length scale controls the behavior of the spin polarization. In in a recent article* in Physical Review Letters, Harvard Physics graduate and currently an Associate in Lukin's group, Norman Yao, together with Prof. Mikhail Lukin and colleagues from University of Washington, Max-Planck-Institut, and BU, examined localization phenomena associated with generic, high entropy, states of a translation-invariant, one-dimensional spin ladder. At early times, the authors find slow growth of entanglement entropy consistent with the known phenomenology of many-body localization in disordered, interacting systems. At intermediate times, however, anomalous diffusion sets in, leading to full spin polarization decay on an exponentially activated time scale. Yao et al. identify a single length scale which parametrically controls both the spin transport times and the apparent divergence of the susceptibility to spin glass ordering. Ultimately, at the latest times, the exponentially slow anomalous diffusion gives way to diffusive thermal behavior. The authors dub the intermediate dynamical behavior, which persists over many orders of magnitude in time, quasi-many-body localization.


*N.Y. Yao, C.R. Laumann, J.I. Cirac, M.D. Lukin, and J.E. Moore, "Quasi-Many-Body Localization in Translation-Invariant Systems," Phys. Rev. Lett. 117, 240601 (7 December 2016) DOI: 10.1103/PhysRevLett.117.240601.