The Anderson Model out of Equilibrium: Non-Crossing-Approximation Approach to Transport through a Quantum Dot

TL;DR

This paper applies the non-crossing approximation to study the non-equilibrium transport properties of the infinite-U Anderson model in a quantum dot, revealing how the Kondo effect influences conductance under various conditions.

Contribution

It introduces a non-crossing approximation approach to analyze non-equilibrium transport in the Anderson model, highlighting the effects of bias and temperature on the Kondo resonance.

Findings

Kondo peak enhances low-temperature conductance

Finite bias splits the Kondo peak and reduces conductance

Zero magnetic field shows broadened and shifted conductance peaks

Abstract

The infinite-U Anderson model is applied to transport through a quantum dot. The current and density of states are obtained via the non-crossing approximation for two spin-degenerate levels weakly coupled to two leads. At low temperatures, the Kondo peak in the equilibrium density of states strongly enhances the linear-response conductance. Application of a finite voltage bias reduces the conductance and splits the peak in the density of states. The split peaks, one at each chemical potential, are suppressed in amplitude by a finite dissipative lifetime. We estimate this lifetime perturbatively as the time to transfer an electron from the higher chemical potential lead to the lower chemical potential one. At zero magnetic field, the clearest signatures of the Kondo effect in transport through a quantum dot are the broadening, shift, and enhancement of the linear-response conductance peaks at low temperatures, and a peak in the nonlinear differential conductance around zero bias.