Nonequilibrium conductance of a nanodevice for small bias voltage

TL;DR

This paper uses non-equilibrium renormalized perturbation theory to analyze the conductance of a quantum dot under small bias, considering electron-hole asymmetry and intermediate valence, providing exact linear response terms.

Contribution

It introduces a detailed calculation of conductance and self energies for quantum dots with asymmetries, extending previous models to more general conditions.

Findings

Conductance G has a linear V term when asymmetries are present.

Exact expressions for linear terms in omega and V are derived.

Results simplify under symmetric voltage drop conditions.

Abstract

Using non-equilibrium renormalized perturbation theory, we calculate the retarded and lesser self energies, the spectral density rho(omega) near the Fermi energy, and the conductance G through a quantum dot as a function of a small bias voltage V, in the general case of electron-hole asymmetry and intermediate valence. The linear terms in omega and V are given exactly in terms of thermodynamic quantities. When the energy necessary to add the first electron (Ed) and the second one (Ed+U) in the quantum dot are not symmetrically placed around the Fermi level, G has a linear term in V if in addition either the voltage drop or the coupling to the leads is not symmetric. The effects of temperature are discussed. The results simplify for a symmetric voltage drop, a situation usual in experiment.