Nonequilibrium Critical Behavior for Electron Tunneling through Quantum Dots in an Aharonov-Bohm Circuit

TL;DR

This paper investigates the nonequilibrium critical behavior of electron tunneling through double quantum dots in an Aharonov-Bohm circuit, revealing universal conductance behavior and rectification effects near a quantum critical point.

Contribution

It generalizes previous series configuration studies to a parallel setup with flux, providing exact results for conductance across the quantum critical crossover.

Findings

Universal conductance formula at finite temperature and voltage.

Asymmetry in conductance leads to current rectification.

Identification of non-Fermi liquid to Fermi liquid crossover behavior.

Abstract

Double quantum dots can provide an experimental realization of the 2 impurity Kondo model which exhibits a non-Fermi liquid quantum critical point (QCP) at a special value of its parameters. We generalize our recent study of double quantum dots in series \cite{Sela08} to a parallel configuration with an Aharonov-Bohm flux. We present an exact universal result for the finite temperature and finite voltage conductance $G[V,T]$ along the crossover from the QCP to the low energy Fermi liquid phase. Compared to the series configuration, here generically $G[V,T] \ne G[-V,T]$, leading to current rectification.