Electrical control of the exciton–biexciton splitting in self-assembled InGaAs quantumdots

Abstract

The authors demonstrate how lateral electric fields can be used to precisely control theexciton–biexciton splitting in InGaAs quantum dots. By defining split-gate electrodes onthe sample surface, optical studies show how the exciton transition can be tuned intoresonance with the biexciton by exploiting the characteristically dissimilar DC Starkshifts. The results are compared to model calculations of the relative energiesof the exciton and biexciton, demonstrating that the tuning can be traced toa dominance of hole–hole repulsion in the presence of a lateral field. Cascadeddecay of the exciton–biexciton system enables the generation of entangled photonpairs without the need to suppress the fine structure splitting of the exciton.Our results demonstrate how the exciton–biexciton system can be electricallycontrolled.