Correlation Effects in Side-Coupled Quantum Dots

TL;DR

This paper uses numerical renormalization group techniques to analyze correlation effects in double and triple quantum dot systems, revealing complex Kondo phenomena and phase regimes influenced by electron-phonon interactions.

Contribution

It introduces a detailed phase diagram for double quantum dots and explores the impact of negative Hubbard U and multi-stage Kondo effects in triple quantum dots.

Findings

Identification of different regimes in the DQD phase diagram

Observation of coexisting spin and charge Kondo states

Detection of multi-stage Kondo screening in TQD systems

Abstract

Using Wilson's numerical renormalization group (NRG) technique we compute zero-bias conductance and various correlation functions of a double quantum dot (DQD) system. We present different regimes within a phase diagram of the DQD system. By introducing a negative Hubbard U on one of the quantum dots, we simulate the effect of electron-phonon coupling and explore the properties of the coexisting spin and charge Kondo state. In a triple quantum dot (TQD) system a multi-stage Kondo effect appears where localized moments on quantum dots are screened successively at exponentially distinct Kondo temperatures.