Entangled photon pair generation in hybrid superconductor–semiconductor quantum dot devices

Abstract

We investigate the effect of Cooper pair injection in shifting the biexciton energy level of low-symmetry (${C}_{2v}$) quantum dots (QDs) exhibiting nontrivial fine structure splitting. Coupling QDs to the superconducting coherent state forms extra fine structures by intermixing the ground and biexcitonic states where spectroscopic separation of neutral exciton and biexciton can be diminished, yielding a system to be utilized in the time reordering scheme. The separability of exciton and biexciton energy levels is ascribed to the corresponding direct, exchange, and correlation energies calculated here through the configuration interaction method. We demonstrate the possibility of enhancing photon entanglement concurrence via providing an energy coincidence for biexciton-exciton ($XX$ \ensuremath{\rightarrow} $X$) and exciton-ground ($X$ \ensuremath{\rightarrow} 0) emissions within the weak coupling regime.