Optically Probing Spin and Charge Interactions in an Tunable Artificial Molecule

TL;DR

This study uses optical techniques to investigate and control the spin and charge interactions within a tunable artificial molecule, revealing detailed quantum couplings and effects in a single-electron system.

Contribution

It provides the first detailed optical characterization and electrical control of charge and spin interactions in a single, tunable quantum dot molecule.

Findings

Charge and spin dependent inter-dot couplings are optically probed.

Coulomb and Pauli blockade effects are directly observed.

Inter-dot quantum coupling is mainly mediated by electron tunneling.

Abstract

We optically probe and electrically control a single artificial molecule containing a well defined number of electrons. Charge and spin dependent inter-dot quantum couplings are probed optically by adding a single electron-hole pair and detecting the emission from negatively charged exciton states. Coulomb and Pauli blockade effects are directly observed and hybridization and electrostatic charging energies are independently measured. The inter-dot quantum coupling is confirmed to be mediated predominantly by electron tunneling. Our results are in excellent accord with calculations that provide a complete picture of negative excitons and few electron states in quantum dot molecules.