Fig. 5.

Quantum entanglement between polarization and 10,010ħ of OAM. We recorded correlations in the coincidence counts between Alice’s polarization measurements and Bob’s OAM measurements of superposition states. Again, the OAM superpositions are measured by detecting transmitted photons behind a slit mask that mimics the superposition structure. The circular rotation of the mask (<0.018°) is approximated by a linear translation. The colored region below each fringe corresponds to the accidental coincidence detections, derived from single counts and a measured coincidence window of 4.69 ± 0.34 ns. The error bars show Poissionian error estimation. The lines correspond to the best sin²-fit function with the condition to be above the accidentals to have nonnegative coincidence rates. From the visibilities of the fitted functions we derived entanglement witness value above the classical bound.