Integrability and ideal conductance at finite temperatures

TL;DR

This paper investigates how integrability influences finite-temperature charge conductance in one-dimensional systems, showing that integrable models exhibit ideal conductance while nonintegrable ones do not.

Contribution

It provides analytical and numerical evidence linking integrability to finite charge stiffness at finite temperatures in one-dimensional quantum systems.

Findings

Finite D(T>0) in integrable systems with equal masses.

Vanishing D(T>0) in nonintegrable systems with unequal masses.

Conjecture that finite D(T>0) is a universal feature of integrable models.

Abstract

We analyse the finite temperature charge stiffness D(T>0), by a generalization of Kohn's method, for the problem of a particle interacting with a fermionic bath in one dimension. We present analytical evidence, using the Bethe ansatz method, that D(T>0) is finite in the integrable case where the mass of the particle equals the mass of the fermions and numerical evidence that it vanishes in the nonintegrable one of unequal masses. We conjecture that a finite D(T>0) is a generic property of integrable systems.