title: The quest for three-color entanglement: experimental investigation of new multipartite quantum correlations.
abstract: We experimentally investigate quadrature correlations between pump, signal, and idler fields in an above-threshold optical parametric oscillator. We observe new quantum correlations among the pump and signal or idler beams, as well as among the pump and a combined quadrature of signal and idler beams. A further investigation of unforeseen classical noise observed in this system is presented, which hinders the observation of the recently predicted tripartite entanglement. In spite of this noise, current results approach the limit required to demonstrate three-color entanglement.
authors: Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, São Paulo, SP, Brazil 05315-970.
authors: K N
authors: KN
authors: Cassemiro
authors: A S
authors: AS
authors: Villar
authors: M
authors: M
authors: Martinelli
authors: P
authors: P
authors: Nussenzveig
mesh_terms: D003116:Color; D003124:Colorimetry / Q000379:methods*; D003198:Computer Simulation; D007834:Lasers; D008027:Light; D008962:Models, Theoretical; D011789:Quantum Theory; D012542:Scattering, Radiation