Electron localization and entanglement in a two-electron quantum dot

TL;DR

This paper investigates how two electrons in an elliptic quantum dot can localize and entangle, using advanced computational methods, with results aligning well with experimental data, informing quantum computing applications.

Contribution

It introduces a method combining symmetry breaking and restoration to model electron localization and entanglement in quantum dots, matching experimental observations.

Findings

Electrons can localize and form a molecular dimer in elliptic quantum dots.

Calculated singlet-triplet splitting matches cotunneling measurements.

Knowledge of dot shape and J(B) enables estimation of entanglement degree.

Abstract

Calculations for two electrons in an elliptic quantum dot, using symmetry breaking at the unrestricted Hartree-Fock level and subsequent restoration of the broken parity via projection techniques, show that the electrons can localize and form a molecular dimer, described by a Heitler-London-type wave function. The calculated singlet-triplet splitting (J) as a function of the magnetic field (B) agrees with cotunneling measurements. Knowledge of the dot shape and of J(B) allows determination of the degree of entanglement in the ground state of the dot, which is of interest for the implementation of quantum logic gates. The theoretical value agrees with the experimental estimates.