Effect of the Coulomb interaction on the electron relaxation of weakly-confined quantum dot systems

TL;DR

This study investigates how Coulomb interactions influence electron relaxation in weakly-confined quantum dots, revealing that electron correlations generally slow relaxation processes and that multi-electron systems exhibit greater stability than single-electron counterparts.

Contribution

The paper provides a detailed analysis of electron relaxation mechanisms in multi-electron quantum dots, highlighting the effects of Coulomb interactions and external magnetic fields on relaxation rates.

Findings

Electron correlations reduce transition rates compared to single-electron systems.

Piezoelectric scattering becomes dominant as electron number increases.

Multi-electron quantum dots are more stable than single-electron ones.

Abstract

We study acoustic-phonon-induced relaxation of charge excitations in single and tunnel-coupled quantum dots containing few confined interacting electrons. The Full Configuration Interaction approach is used to account for the electron-electron repulsion. Electron-phonon interaction is accounted for through both deformation potential and piezoelectric field mechanisms. We show that electronic correlations generally reduce intradot and interdot transition rates with respect to corresponding single-electron transitions, but this effect is lessened by external magnetic fields. On the other hand, piezoelectric field scattering is found to become the dominant relaxation mechanism as the number of confined electrons increases. Previous proposals to strongly suppress electron-phonon coupling in properly designed single-electron quantum dots are shown to hold also in multi-electron devices. Our results indicate that few-electron orbital degrees of freedom are more stable than single-electron ones.