Universality of equilibrium one-dimensional transport from gauge invariance

TL;DR

This paper demonstrates that gauge invariance ensures the universal conductance value of e^2/h in one-dimensional electron systems, regardless of interactions, provided two conserved charges are present.

Contribution

It introduces a gauge invariance-based argument to establish conductance universality beyond the Luttinger model in 1D systems.

Findings

Conductance remains universal at e^2/h per channel per spin.

Gauge invariance protects the conductance against interaction effects.

Two conserved charges are essential for the universality.

Abstract

In this letter we address the question how interactions affect the DC conductance of a one-dimensional electron system not necessarily adequately described by the Luttinger model. Using a Laughlin type argument, we show that gauge invariance protects the universal value of the conductance of $e^2/h$ per channel per spin orientation if the system possesses two conserved charges conjugate to the chemical potentials of the external reservoirs.