Polarization-entangled photon-pair source using beam displacers and thin crystals

We present an experimental implementation of a polarization-entangled photon-pair source based on beam displacers. The down-converted photons are emitted via spontaneous parametric downconversion in a non-degenerate and type-0 process. We obtain a state fidelity of F = 0.975 ± 0.004 and violate a Clauser–Horne–Shimony–Holt (CHSH) inequality with S = 2.75 ± 0.01. Our source also uses thin crystals for applications in quantum imaging, taking advantage of the large number of spatial modes. We estimate that our source could produce 550 ± 12 spatial modes.