1 research outputs found
The internal clock of many-body delocalization
After a decade of many claims to the opposite, there now 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 imbalance
and its temporal fluctuations , the entanglement and Renyi
entropies, and , in a 1D
system of interacting disordered fermions. We observe that adopting
as a measure for the internal
time per sample reduces the sample-to-sample fluctuations but does not
eliminate them. However, a (nearly) perfect collapse of the average
and for different
is obtained when plotted against or
, indicating that the average entropy
appropriately models the ensemble-averaged internal clock. We take the tendency
for faster-than-logarithmic growth of
together with smooth dependency on 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.Comment: 15 pages, 12+5 figures, published versio