Quantum transport in a multiple dot system : charge Kondo effects in a quadruple dot

Abstract

The Kondo effect is a phenomenon that when the electron in quantum dot and the electron in electron reservoir have antiferromagnetic interaction, the conductance through the quantum dot increases as the temperature decreases. The Kondo effect in the quantum dot system is the one of the most important field of the mesoscopic physics, and a lots of studies have been done both theoretically and experimentally. As the quantum-dot-fabrication skill has improved, new types of Kondo effects like orbital Kondo effects and charge Kondo effects are realized. Recently, there is a theoretical study on the charge Kondo effect with the triple quantum dot system, and multiple quantum dot systems where the charge Kondo effect is expected to occur, are realized experimentally. In this dissertation, we perform the following theoretical studies to understand charge Kondo effects with the quadruple quantum dot system which realized experimentally. First, we find the regimes that the charge Kondo effect can appear and analyze the each charge Kondo effect. Second, we calculate the conductance that can be measured in the 2-dimensional electron gas system or carbon nanotube system to understand charge Kondo effects. Also, we find that the new type of conductance measurement can confirm the Kondo effect and this measurement can be applied easily.