Transient and persistent particle subdiffusion in a disordered chain coupled to bosons

TL;DR

This paper investigates how a single particle propagates in a disordered chain coupled to bosons, revealing that noninteracting bosons enable transient subdiffusion transitioning to normal diffusion, while hard-core bosons sustain persistent subdiffusion, with implications for many-body localization.

Contribution

It distinguishes the effects of noninteracting versus hard-core bosons on particle transport in disordered systems, highlighting the role of multi-boson processes and many-body effects.

Findings

Noninteracting bosons lead to transient subdiffusion transitioning to normal diffusion.

Hard-core bosons suppress multi-boson processes, resulting in persistent subdiffusive transport.

Quasiperiodic potentials exhibit stable long-time diffusion.

Abstract

We consider the propagation of a single particle in a random chain, assisted by the coupling to dispersive bosons. Time evolution treated with rate equations for hopping between localized states reveals a qualitative difference between dynamics due to noninteracting bosons and hard-core bosons. In the first case the transient dynamics is subdiffusive, but multi-boson processes allow for long-time normal diffusion, while hard-core effects suppress multi-boson processes leading to persistent subdiffusive transport, consistent with numerical results for a full many-body evolution. In contrast, analogous study for a quasiperiodic potential reveals a stable long-time diffusion.