Periodic and Aperiodic Bunching in the Addition Spectra of Quantum Dot

TL;DR

This study investigates the electron addition spectra of quantum dots, revealing a transition from random to periodic bunching of electron additions as the number of electrons increases, linked to spatially distinct regions within the dots.

Contribution

It uncovers a transition from random to periodic electron bunching in quantum dots, highlighting spatial inhomogeneity in electron addition processes.

Findings

Electron additions form bunches rather than being evenly spaced.

Bunching transitions from random to periodic around every fifth electron.

Periodic bunching correlates with electron additions into distinct spatial regions.

Abstract

We study electron addition spectra of quantum dots in a broad range of electron occupancies starting from the first electron. Spectra for dots containing <200 electrons reveal a surprising feature. Electron additions are not evenly spaced in gate voltage. Rather, they group into bunches. With increasing electron number the bunching evolves from occurring randomly to periodically at about every fifth electron. The periodicity of the bunching and features in electron tunneling rates suggest that the bunching is associated with electron additions into spatially distinct regions within the dots.