Disorder and interaction induced pairing in the addition spectra of quantum dots

TL;DR

This study numerically explores how strong disorder and electron interactions in small quantum dots lead to pairing phenomena, resembling experimental electron bunching effects.

Contribution

It reveals disorder and interaction-induced pairing in quantum dots, linking numerical results to experimentally observed electron bunching.

Findings

Identification of regimes with close electron addition energies

Correlation between pairing and electron puddles within the dot

Connection of results to experimental bunching phenomena

Abstract

We have investigated numerically the electron addition spectra in quantum dots containing a small number (N < 11) of interacting electrons, in presence of strong disorder. For a short-range Coulomb repulsion, we find regimes in which two successive electrons enter the dot at very close values of the chemical potential. In the strongly correlated regime these close additions, or pairing, are associated with electrons tunneling into distinct electron puddles within the dot. We discuss the tunneling rates at pairing, and we argue that our results are related to a phenomenon known as "bunching", recently observed experimentally.