Two electrons in a strongly coupled double quantum dot: from an artificial helium atom to a hydrogen molecule

TL;DR

This paper investigates how two electrons in a double quantum dot transition from an artificial helium atom to a hydrogen molecule as the barrier potential varies, using variational wavefunctions to analyze their states and magnetic field effects.

Contribution

It introduces variational wavefunctions for accurately modeling two electrons in a single dot and studies their evolution in a double dot system with changing barrier potential.

Findings

The singlet-triplet gap varies with barrier potential and magnetic field.

The system transitions from helium-like to hydrogen-like states as the barrier increases.

Variational wavefunctions effectively describe strongly coupled two-electron states.

Abstract

We study the formation of molecular states in a two-electron quantum dot as a function of the barrier potential dividing the dot. The increasing barrier potential drives the two electron system from an artificial helium atom to an artificial hydrogen molecule. To study this strongly coupled regime, we introduce variational wavefunctions which describe accurately two electrons in a single dot, and then study their mixing induced by the barrier. The evolution of the singlet-triplet gap with the barrier potential and with an external magnetic field is analyzed.