Multi-dimensional photonic entanglement: Tuning the number of modes
Bart-Jan Pors, Sumant S. R. Oemrawsingh, Martin P. Van Exter, E. R. Eliel, J. P. Woerdman · 2007
Type-I collinear phase matching is used to generate spatially correlated twin-photons. The detection device consists of a single mode fiber and a phase plate, that can be rotated. Coincidence rates as a function of relative rotation angle between the two phase plates are recorded. As the aperture is being closed, the effective number of modes is reduced.