Theory of excitonic spectra and entanglement engineering in dot molecules

TL;DR

This paper investigates the excitonic spectra and entanglement in vertically stacked InGaAs/GaAs quantum dots, revealing complex effects of strain, geometry, and band mixing on optical activity and entanglement, with implications for quantum information applications.

Contribution

It introduces a correlated pseudopotential approach to analyze excitonic states and entanglement in dot molecules, highlighting effects overlooked by previous models.

Findings

All four lowest excitonic states are optically active at small interdot distances.

Entanglement of exciton wavefunctions is highly sensitive to interdot separation.

Strategies for spectroscopic identification and maximization of exciton entanglement are proposed.

Abstract

We present results of correlated pseudopotential calculations of an exciton in a pair of vertically stacked InGaAs/GaAs dots. Competing effects of strain, geometry, and band mixing lead to many unexpected features missing in contemporary models. The first four excitonic states are all optically active at small interdot separation, due to the broken symmetry of the single-particle states. We quantify the degree of entanglement of the exciton wavefunctions and show its sensitivity to interdot separation. We suggest ways to spectroscopically identify and maximize the entanglement of exciton states.