Highly entangled-photon pairs generated from the biexciton cascade transition in a quantum dot-metal nanoparticle hybrid system

摘要

The entanglement between photon pairs generated from the biexciton cascadetransition in a semi- conductor quantum dot located in the vicinity of a metalnanoparticle is theoretically investigated. In the model scheme, thebiexciton-exciton and exciton-ground state transitions are assumed to becoupled to two principal plasmon modes of orthogonal polarizations. For a broadspectral window, because the horizontal and vertical spectra are overlapped,the biexciton and exciton photons are degenerate in energy. This allows us toovercome the natural splitting between the intermediate exciton states.Moreover, the degree of entanglement depends on the geometrical parameters ofthe system. i.e., the radius of the metal nanoparticle and the distance betweenthe quantum dot and the nanoparticle. The results reveal that such a hybridsystem profoundly modifies the photon entanglement even in the absence ofstrong coupling between the emitter and the metal nanosphere.