Generation of (2 × 2) and (4 × 4) two-photon states with tunable degree of entanglement and mixedness



A parametric source of polarization entangled photon pairs with peculiar spatial characteristics allows to generate any kind of bi-partite entangled states with tunable dgree of entanglement and mixedness. In particular, maximally entangled mixed states (MEMS) have been created in a reliable way by a “patchwork” technique and investigated by quantum tomography. By the same source, momentum-polarization hyper-entangled two-photon states have been synthesized. The quality of the entanglement in the two degrees of freedom has been tested by multimode Hong-Ou-Mandel interferometry.