Engineering photon cascades from multiexciton complexes in a self-assembled quantum dot by a lateral electric field

We demonstrate theoretically that by applying an in-plane electric field it is possible to engineer and tune photon cascades originating from recombination of multiexciton complexes confined in self-assembled quantum dots. We find the multiexciton energies and states as functions of the field using the effective-mass configuration-interaction approach with the effects of electron-hole exchange treated perturbatively, and use Fermi's golden rule to compute the emission spectra. We show that the field-induced Stark shift of the energies of photons emitted by the biexciton and two linearly polarized excitons is strongly renormalized by the electron-hole interactions, which are governed by the separation of electrons and holes induced by the field. As a result, the effective Stark shifts of exciton and biexciton emission lines have opposite signs, leading to a removal of the biexciton binding energy at a finite field. This enables the cascade of a pair of polarization entangled photons in the presence of a finite exciton anisotropic exchange splitting. We compare these emission spectra to those of the charged exciton, the triplet biexciton, and the three-exciton complex. We find that the electric field and Coulomb interactions differentiate the biexciton-exciton cascade from other cascades, facilitating identification of its spectra and practical implementation.