Dephasing enhanced spin transport in the ergodic phase of a many‐body localizable system

• Published in: Annalen der Physik 2017-07, Vol.529 (7), p.n/a
• Main Authors: Žnidarič, Marko, Mendoza‐Arenas, Juan Jose, Clark, Stephen R., Goold, John
• Format: Article
• Language: English
• Subjects: Behavior; Competition; Diffusion effects; Disorder; Ergodic processes; many‐body localization; Mathematical models; Size effects; spin transport; Studies; Temperature; Transport
• ISSN: 0003-3804; 1521-3889
• DOI: 10.1002/andp.201600298

We study high temperature spin transport in a disordered Heisenberg chain in the ergodic regime when bulk dephasing is present. We find that while dephasing always renders the transport diffusive, there is nonetheless a remnant of the diffusive to sub‐diffusive transition found in a system without dephasing manifested in the behaviour of the diffusion constant with the dephasing strength. By studying finite‐size effects we show numerically and theoretically that this feature is caused by the competition between large crossover length scales associated to disorder and dephasing that control the dynamics observed in the thermodynamic limit. We demonstrate that this competition may lead to a dephasing enhanced transport in this model. Transport in one‐dimensional systems is strongly inflenced by disorder. Depending on disorder strength, one can have different phases displaying anomalous, diffusive, or insulating behavor. We study how such transport is modified by the coupling to the environment, showing that it always becomes diffusive, though with a remnant of clean phase transitions being imprinted in the dependence of the diffusion constant on the dephasing strength.