Perturbative Approach to the Nonequilibrium Kondo Effect in a Quantum Dot

TL;DR

This paper develops a perturbative theoretical framework for quantum transport in quantum dots under finite bias, revealing how the Kondo resonance splits into double peaks at high voltages, which may relate to conductance anomalies.

Contribution

It introduces a perturbative approach using the Keldysh formalism to analyze nonequilibrium Kondo effects in quantum dots, highlighting the splitting of the Kondo resonance.

Findings

Kondo resonance splits into double peaks when eV > k_B T_K

A second conductance peak appears besides the zero-bias peak

Potential connection to the 0.7 conductance anomaly

Abstract

The theory of quantum transport through a dot under a finite bias voltage is developed using perturbation theory in the Keldysh formalism. It is found that the Kondo resonance splits into double peaks when the voltage exceeds the Kondo temperature, $eV>k_B T_K $, which leads to the appearance of a second peak in conductance, in addition to the zero-bias peak. The possible relevance of the new peak to the 0.7 conductance anomaly observed in quantum point contact is discussed.