Two level anti-crossings high up in the single-particle energy spectrum of a quantum dot

TL;DR

This paper investigates high-energy single-particle energy levels in quantum dots under magnetic fields, revealing unexpected anti-crossings and contrasting current behaviors, modeled through a simple coherent level mixing approach.

Contribution

It provides a detailed analysis of anti-crossings in high-energy levels of quantum dots and introduces a model explaining current variations during level interactions.

Findings

Observed anti-crossings in high-energy levels.

Model successfully explains current behavior during anti-crossings.

Identified regions with unexpected anti-crossing phenomena.

Abstract

We study the evolution with magnetic field of the single-particle energy levels high up in the energy spectrum of one dot as probed by the ground state of the adjacent dot in a weakly coupled vertical quantum dot molecule. We find that the observed spectrum is generally well accounted for by the calculated spectrum for a two-dimensional elliptical parabolic confining potential, except in several regions where two or more single-particle levels approach each other. We focus on two two-level crossing regions which show unexpected anti-crossing behavior and contrasting current dependences. Within a simple coherent level mixing picture, we can model the current carried through the coupled states of the probed dot provided the intrinsic variation with magnetic field of the current through the states (as if they were uncoupled) is accounted for by an appropriate interpolation scheme.