Diffusive transport in a quasiperiodic Fibonacci chain: Absence of many-body localization at weak interactions

Vipin Kerala Varma and Marko Žnidarič
Phys. Rev. B 100, 085105 – Published 1 August 2019

Abstract

We study high-temperature magnetization transport in a many-body spin-1/2 chain with on-site quasiperiodic potential governed by the Fibonacci rule. In the absence of interactions it is known that the system is critical with the transport described by a continuously varying dynamical exponent (from ballistic to localized) as a function of the on-site potential strength. Upon introducing weak interactions, we find that an anomalous noninteracting dynamical exponent becomes diffusive for any potential strength. This is borne out by a boundary-driven Lindblad dynamics as well as unitary dynamics, with agreeing diffusion constants. This must be contrasted to a random potential where transport is subdiffusive at such small interactions. Mean-field treatment of the dynamics for small U always slows down the noninteracting dynamics to subdiffusion, and is therefore unable to describe diffusion in an interacting quasiperiodic system. Finally, briefly exploring larger interactions we find a regime of interaction-induced subdiffusive dynamics, despite the on-site potential itself having no “rare regions.”

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  • Received 13 May 2019

DOI:https://doi.org/10.1103/PhysRevB.100.085105

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Vipin Kerala Varma1,2,3 and Marko Žnidarič4

  • 1Department of Physics and Astronomy, College of Staten Island, CUNY, Staten Island, New York 10314, USA
  • 2Physics program and Initiative for the Theoretical Sciences, The Graduate Center, CUNY, New York, New York 10016, USA
  • 3Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
  • 4Physics Department, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia

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Issue

Vol. 100, Iss. 8 — 15 August 2019

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