A widely tunable few electron droplet

TL;DR

This paper investigates a tunable few-electron quantum dot in GaAs/AlGaAs, demonstrating control over electron states, coupling regimes, and formation of double quantum dots with observable Kondo effects.

Contribution

It introduces a gate design enabling wide-range tuning of a single electron droplet, including transitions to double quantum dots with strong interdot coupling.

Findings

Observation of discrete quantum states in weak coupling regime

Detection of Kondo phenomena at strong coupling and magnetic fields

Ability to distort the droplet into a double quantum dot while controlling electron number

Abstract

Quasi-static transport measurements are employed to characterize a few electron quantum dot electrostatically defined in a GaAs/AlGaAs heterostructure. The gate geometry allows observations on one and the same electron droplet within a wide range of coupling strengths to the leads. The weak coupling regime is described by discrete quantum states. At strong interaction with the leads Kondo phenomena are observed as a function of a magnetic field. By varying gate voltages the electron droplet can, in addition, be distorted into a double quantum dot with a strong interdot tunnel coupling while keeping track of the number of trapped electrons.