Diverging conductance at the contact between random and pure quantum XX spin chains

TL;DR

This paper investigates how conductance behaves at the contact between a pure and a disordered quantum XX spin chain, revealing divergence in conductance as disorder increases, with implications for quantum transport in disordered systems.

Contribution

It introduces a model of coupled pure and random quantum XX spin chains under non-local thermal baths, analyzing conductance behavior and divergence in the infinite-randomness limit.

Findings

Conductance is linear without disorder

A gap opens with increasing disorder strength

Conductance diverges in the infinite-randomness limit

Abstract

A model consisting in two quantum XX spin chains, one homogeneous and the second with random couplings drawn from a binary distribution, is considered. The two chains are coupled to two different non-local thermal baths and their dynamics is governed by a Lindblad equation. In the steady state, a current J is induced between the two chains by coupling them together by their edges and imposing different chemical potentials $\mu$ to the two baths. While a regime of linear characteristics J versus $\Delta$$\mu$ is observed in the absence of randomness, a gap opens as the disorder strength is increased. In the infinite-randomness limit, this behavior is related to the density of states of the localized states contributing to the current. The conductance is shown to diverge in this limit.