Five-partite continuous-variable entanglement generated by cascaded nonlinear processes in only one optical superlattice

Abstract

We theoretically investigate the generation of five-partite continuous-variable (CV) entanglement through injection-seeded non-degenerate optical parametric amplification cascaded two sum-frequency processes in only one optical superlattice without optical cavities. The idle can be generated by optical parametric amplification of pump and signal. Then, one beam will be generated by the cascaded sum-frequency process of pump and idle, and another beam will be produced by the cascaded sum-frequency process of pump and signal in the same optical superlattice. The phase-mismatching in the cascaded nonlinear processes can be compensated by three reciprocals of the optical superlattice by a quasi-phase-matching technique. The conversion dynamics among the cascaded nonlinear processes is analyzed by using a quantum stochastic method. The five-partite entanglement among pump, signal, idle, and two sum-frequency beams are discussed by applying a sufficient inseparability criteria for the five-partite CV entanglement proposed by Van Loock and Furusawa. This scheme of five-partite entanglement generation with different frequencies has potential applications in quantum communication and computation networks.