Admittance and Nonlinear Transport in Quantum Wires, Point Contacts, and Resonant Tunneling Barriers

TL;DR

This paper analyzes the admittance and nonlinear I-V characteristics of mesoscopic conductors, incorporating Coulomb interactions, and explores effects of gates and frequency on quantum wires, point contacts, and resonant tunneling barriers.

Contribution

It generalizes the scattering approach to include Coulomb interactions, providing new insights into admittance and nonlinear transport in mesoscopic systems.

Findings

Admittance of wires with impurities and gates analyzed.

Nonlinear I-V characteristics of double barrier structures studied.

Frequency-dependent admittance for resonant tunneling barriers examined.

Abstract

We present a discussion of the admittance (ac-conductance) and nonlinear I-V-characteristic for a number of mesoscopic conductors. Our approach is based on a generalization of the scattering approach which now includes the effects of the (long-range) Coulomb interaction. We discuss the admittance of a wire with an impurity and with a nearby gate. We extend a discussion of the low-frequency admittance of a quantum point contact to investigate the effects of the gates used to form the contact. We discuss the nonlinear I-V characteristic of a resonant double barrier structure and discuss the admittance for the double barrier for a large range of frequencies. Our approach emphasizes the overall conservation of charge (gauge invariance) and current conservation and the resulting sum rules for the admittance matrix and nonlinear transport coefficients.