Kondo Resonance Decoherence by an External Potential

TL;DR

This paper investigates how an external bias affects the Kondo resonance in a quantum dot, analyzing the transition from strong to weak coupling regimes through a perturbative approach.

Contribution

It introduces a consistent equations of motion method based on a slave-boson Hamiltonian to analyze Kondo decoherence under bias.

Findings

Weak coupling regime occurs at voltages above a few times the Kondo temperature.

Calculated spectral density and conductance show bias-induced decoherence effects.

Decoherent rate increases with external bias, leading to regime transition.

Abstract

The Kondo problem, for a quantum dot (QD), subjected to an external bias, is analyzed in the limit of infinite Coulomb repulsion by using a consistent equations of motion method based on a slave-boson Hamiltonian. Utilizing a strict perturbative solution in the leads-dot coupling, T, to T^4 and T^6 orders, we calculate the QD spectral density and conductance, as well as the decoherent rate that drive the systemm from the strong to the weak coupling regime. Our results indicate thet the weak coupling regime is reached for voltages larger than a few units of the Kondo temperature.