Tuning the tunnel coupling of quantum dot molecules with longitudinal magnetic fields

TL;DR

This paper demonstrates that longitudinal magnetic fields can tune the energy splitting of hole states in quantum dot molecules, enabling a switch from bonding to antibonding ground states through spin-orbit interaction effects.

Contribution

It introduces a novel method to control the molecular ground state in quantum dot molecules using magnetic fields to manipulate spin-orbit interactions.

Findings

Energy splitting can be tuned to zero and negative values with magnetic fields.

Magnetic fields induce a bonding-to-antibonding ground state transition.

Spin-orbit interaction enhancement is key to the effect.

Abstract

We show that the energy splitting between the bonding and antibonding molecular states of holes in vertically stacked quantum dots can be tuned using longitudinal magnetic fields. With increasing field, the energy splitting first decreases down to zero and then to negative values, which implies a bonding-to-antibonding ground state transition. This effect is a consequence of the enhancement of the valence band spin-orbit interaction induced by the magnetic field, and it provides a flexible mechanism to switch the molecular ground state from bonding to antibonding.