Scheme to generate three-mode continuous-variable entanglement in cavity quantum electrodynamics

We propose a theoretical method of generating a three-mode continuous-variable entanglement in an optical cavity with an atomic cloud. The scheme uses Raman transitions between stable atomic ground states and under the input-output theory a three-mode entangled light of the output fields can be produced. The characters of the tripartite entanglement, the degree of the quadrature-phase amplitude correlations among the three modes are discussed by applying a sufficient inseparability criterion for multipartite continuous-variable entanglement, which was proposed by van Loock and Furusawa. The dependences of the correlation on the effective coupling constants are theoretically analyzed.