Generation of entangled photon pair from biexciton cascade decay in quantum dots

This work presents a theoretical and computational investigation of biexcitonic decay processes in GaAs QDs for the generation of entangled photon pairs (EPP). Entangled photon pairs (EPP) are important in quantum optics and essential for quantum information, quantum teleportation, quantum key distribution, and controlled logic operations. Semiconductor quantum dots (QD) are especially well suited for the generation of EPP and have been proven to have high-entanglement fidelity, extraction efficiency, and photon indistinguishability. QDs have been shown to be good candidates for entangled photon generation. We have used the electron-hole multicomponent coupled-cluster theory (eh-mcCC) for treating the excitonic and biexcitonic states. We have included light-matter interaction in the eh-mcCC method using the dressed-atom approach and the time-propagation is performed diagrammatically. The inclusion of spin states and spin-orbit coupling is crucial for EPP generation and was included in the eh-mcCC formulation using the spin-orbit relativistic effective potential (SOREP) method. The developed method was applied on a series of GaAs QDs and discussions exciton binding energies, biexciton binding energies, fine-structure splitting, and photon-entanglement characteristics will be presented. The results from this study demonstrate size-effect and chemical design parameters needed for the generation of highly-entangled photons from quantum dots.