Coulomb blockade of a noisy metallic box: A realization of Bose-Fermi Kondo models

TL;DR

This paper investigates how voltage noise in a metallic quantum dot system influences Coulomb blockade, revealing that environmental fluctuations can significantly modify the Kondo fixed point and enhance Coulomb blockade effects.

Contribution

It introduces a model incorporating environmental noise via Caldeira-Leggett oscillators into the Bose-Fermi Kondo framework, showing the impact on Coulomb blockade in quantum dots.

Findings

Voltage noise amplifies Coulomb blockade effects.

Zero-point environmental fluctuations alter the Kondo fixed point.

Environmental coupling can significantly modify quantum dot behavior.

Abstract

We focus on a metallic quantum dot coupled to a reservoir of electrons through a single-mode quantum point contact and capacitively connected to a back-gate, by taking into account that the gate voltage can exhibit noise; This will occur when connecting the gate lead to an external transmission line with a finite Ohmic resistance. The voltage (charge) fluctuations at the back gate can be described through a Caldeira-Leggett model of harmonic oscillators. For weak tunneling between the lead qnd the dot, exploiting the anisotropic Bose-Fermi Kondo model, we show that zero-point fluctuations of the environment can markedly alter the previous Matveev Kondo fixed point leading to an amplification of the Coulomb blockade phenomenon.