Gate voltage effects in capacitively coupled quantum dots

TL;DR

This paper investigates how gate voltage influences the Kondo effect and electron transport in capacitively coupled quantum dots, revealing significant variations in low-energy scales and charge fluctuations.

Contribution

It provides a detailed analysis of gate voltage effects on Kondo physics and charge dynamics in coupled quantum dots using numerical renormalization group and scaling methods.

Findings

Kondo scale varies exponentially with gate voltage.

Charge fluctuations increase near Coulomb blockade edges.

Transport properties are strongly affected by gate tuning.

Abstract

We study a system of two symmetrical capacitively coupled quantum dots, each coupled to its own metallic lead, focusing on its evolution as a function of the gate voltage applied to each dot. Using the numerical renormalization group and poor man's scaling techniques, the low-energy Kondo scale of the model is shown to vary significantly with the gate voltage, being exponentially small when spin and pseudospin degrees of freedom dominate; but increasing to much larger values when the gate voltage is tuned close to the edges of the Coulomb blockade staircase where low-energy charge-fluctuations also enter, leading thereby to correlated electron physics on energy/temperature scales more accessible to experiment. This range of behaviour is also shown to be manifest strongly in single-particle dynamics and electron transport through each dot.