Phonon-assisted tunneling between singlet states in two-electron quantum dot molecules

TL;DR

This paper investigates phonon-assisted tunneling between singlet states in two-electron quantum dot molecules, revealing rapid relaxation processes influenced by Coulomb interaction and electron-phonon coupling mechanisms.

Contribution

It provides a detailed analysis of singlet-singlet relaxation in two-electron quantum dots, highlighting the effects of Coulomb interaction and different electron-phonon couplings.

Findings

Relaxation rates are similar for single and two-electron systems but shifted by Coulomb interaction.

Phonon-induced tunneling occurs on the order of tens of picoseconds.

Deformation potential and piezoelectric coupling have distinct influences on tunneling rates.

Abstract

We study phonon-assisted electron tunneling in semiconductor quantum dot molecules. In particular, singlet-singlet relaxation in a two-electron doped structure is considered. The influence of Coulomb interaction is discussed via comparison with a single electron system. We find that the relaxation rate reaches similar values in the two cases but the Coulomb interaction shifts the maximum rates towards larger separations between the dots. The difference in electron-phonon interaction between deformation potential and piezoelectric coupling is investigated. We show that the phonon-induced tunneling between two-electron singlet states is a fast process, taking place on the time scales of the order of a few tens of picoseconds.