Exchange interaction and stability diagram of coupled quantum dots in magnetic fields

TL;DR

This paper investigates how magnetic fields influence the charge stability and exchange interactions in coupled quantum dots with up to two electrons, revealing the dependence of coupling strength on magnetic field variations.

Contribution

The study provides exact diagonalization calculations of chemical potentials and exchange energies, analyzing magnetic field effects on inter-dot coupling in quantum dots.

Findings

Inter-dot coupling decreases with increasing magnetic fields.

Chemical potential curvatures vary with magnetic field and bias.

Exchange energies are smaller than estimates from stability diagrams.

Abstract

The charge stability diagram for two coupled quantum dots containing up to two electrons is computed in magnetic fields. One- and two-particle Schroedinger equations are solved by exact diagonalization to obtain the chemical potentials and exchange energy in these systems. By analyzing the chemical potentials variation with external biases and magnetic fields, it is possible to distinguish between the weak and strong inter-dot couplings. The variation of the chemical potential curvatures and the double-triple point separations in the stability diagrams confirms the inter-dot coupling decrease with increasing magnetic fields. The computed exchange energies are also found to be significantly smaller than the values estimated from the stability diagram.