Direct production of three-color polarization entanglement for continuous variable

摘要

The direct generation of discrete-variable three-photon polarization entanglement has been recently demonstrated [Nat. Photonics 8, 801 (2014)]. Here, we propose a feasible scheme to generate continuous-variable (CV) three-color polarization entangled states of light in a deterministic way. The method initially prepares a tripartite quadrature entanglement based on two cascaded nondegenerate optical parametric oscillators. The entangled modes are then coupled, respectively, with three strong coherent optical beams on polarized beam splitters, leading to the generation of the three-color CV polarization entanglement. The polarization entanglement is then verified by inseparability criterion and positive partial transposition criterion. Additionally, optimal parameters in practical conditions are obtained through numerical simulations, which could provide useful guidance for experimental implementations. The demonstrated CV three-color polarization entanglement is suitable in quantum information processing tasks relying on the direct interaction between spin of atoms and polarization of light. (C) 2015 Optical Society of America