Deterministic Preparation of a Hyper-Entangled Three-Photon Asymmetric W State Assisted by the Single-Sided QD-Cavity System

Hyper-entangled states that encode qubits in multiple degrees of freedom of a quantum system can provide a decisive advantage in quantum information processing, such as improving the capacity of communication and speeding up the computation. Assisted by quantum dots in single-sided optical microcavities, nonlinear interaction of optical circular polarizations is induced and a deterministic scheme for preparing a three-photon hyper-entangled asymmetric W state with polarization degree of freedom and spatial degree of freedom is proposed. The preparing process is composed of three steps: the preparation of a three-photon polarization entangled asymmetric W state; the preparation of a three-photon spatial entangled asymmetric W state; the preparation of a three-photon hyper-entangled asymmetric W state. It can be generalized to generate a three-photon general W state according to practical requirement.