Critical conductance of a one-dimensional doped Mott insulator

TL;DR

This paper investigates the conductance behavior of a one-dimensional doped Mott insulator near a quantum phase transition, highlighting the special role of the Luther-Emery point and the effects of lead properties on conductance.

Contribution

It provides a detailed analysis of conductance at the Luther-Emery point and how deviations affect temperature dependence in a one-dimensional Mott insulator.

Findings

Conductance at the Luther-Emery point is described by free fermion propagation.

Temperature dependence follows a Fermi function at the Luther-Emery point.

Deviations from the Luther-Emery point qualitatively change conductance behavior.

Abstract

We consider the two-terminal conductance of a one-dimensional Mott insulator undergoing the commensurate-incommensurate quantum phase transition to a conducting state. We treat the leads as Luttinger liquids. At a specific value of compressibility of the leads, corresponding to the Luther-Emery point, the conductance can be described in terms of the free propagation of non-interacting fermions with charge e/\sqrt{2}. At that point, the temperature dependence of the conductance across the quantum phase transition is described by a Fermi function. The deviation from the Luther-Emery point in the leads changes the temperature dependence qualitatively. In the metallic state, the low-temperature conductance is determined by the properties of the leads, and is described by the conventional Luttinger liquid theory. In the insulating state, conductance occurs via activation of e/\sqrt{2} charges, and is independent of the Luttinger liquid compressibility.