Generation of entangled photon pairs by semiconductor quantum dots in a structure of quantum cellular automata

We propose a unique scheme to generate entangled photon pairs by six semiconductor quantum dots in a structure of quantum cellular automata. By means of interdot electronic tunneling, single-electron spin manipulation, and auxiliary excitons, we can convert the entanglement from the charge degrees of freedom of the electrons to the spin degrees of freedom of the electrons, and then to the polarization of the photons. Our scheme presents a source of entangled photon pairs without using spin-spin coupling, which could work repeatedly, deterministically and efficiently. Both the experimental challenge and the feasibility with present technologies are discussed. In comparison with former relevant work, our proposal not only gives an alternative method to generate entangled photons, but is applicable to other quantum information processing tasks with free electrons.