The Joint Condensed Matter Seminar (JCMS) series is organised by KTH Royal Insitute of Technology, Nordita, and Stockholm University.
On Monday, September 11th, 2023 from 11 am to 12 am we will host a seminar by Soumya Bera from Indian Institute of Technology, Bombay.
Internal clock for many-body delocalization
There is a growing consensus that generic disordered quantum wires, e.g. the XXZ-Heisenberg chain, do not exhibit many-body localization (MBL) - at least not in a strict sense within a reasonable window of disorder values. Specifically, computational studies of short wires exhibit an extremely slow but unmistakable flow of physical observables with increasing time and system size (`creep’) that is consistently directed away from (strict) localization. Our work sheds fresh light on delocalization physics: Strong sample-to-sample fluctuations indicate the absence of a generic time scale, i.e., of a naive “clock rate”; however, the concept of an “internal clock” survives, at least in an ensemble sense. Specifically, we investigate the relaxation of the charge imbalance and the entanglement entropy in a 1D system of interacting disordered fermions. We observe that the average entropy appropriately models the ensemble-averaged internal clock and reduces fluctuations. We take the tendency for faster-than-logarithmic growth of entanglement and smooth dependency on the disorder of all our observables within the entire simulation window as support for the cross-over scenario, discouraging an MBL transition within the traditional parametric window of computational studies.
[1] F. Evers, and S. Bera. “The internal clock of many-body (de-) localization” arXiv:2302.11384.