Conductance and conductance fluctuations of narrow disordered quantum wires

TL;DR

This study investigates how boundary roughness and impurity islands affect conductance and its fluctuations in narrow disordered quantum wires, revealing the destruction of conductance quantization and the impact of Anderson localization.

Contribution

It provides a detailed analysis of conductance behavior in disordered quantum wires using Green's function techniques, highlighting the effects of different disorder types.

Findings

Strong scattering destroys conductance quantization

Anderson localization limits high mobility

Conductance fluctuations can be length-independent

Abstract

In this paper we present and discuss our results for the conductance and conductance fluctuations of narrow quantum wires with two types of disorder: boundary roughness (hard wall confining potential) and islands of strongly scattering impurities within the bulk of the wire. We use a tight--binding Hamiltonian to describe the quantum wire, infinite perfect leads, a two--terminal Landauer--type formula for the conductance, and the recursive single-particle Green's function technique. We find that conductance quantization is easily destroyed by strong scattering. We also find that Anderson localization poses a serious restriction on the high carrier mobility predicted in quantum wires. Conductance fluctuations in narrow quantum wires are not, in general, universal (as in the metallic regime), but can be independent of the wire length over a short range of lengths.