Experimental method for measuring classical concurrence of generic beam   shapes
  Classical entanglement is a powerful tool which provides a neat numerical estimate for the study of classical correlations. Its experimental investigation, however, has been limited to special cases. Here, we demonstrate that the experimental quantification of the level of classical entanglement can be carried out in more general instances. Our approach enables the extension to arbitrarily shaped transverse modes and hence delivering a suitable quantification tool to describe concisely the modal structure. 
E. Roccia, I. Gianani, L. Mancino, M. Sbroscia, I. Miatka, F. Somma,   and M. Barbieri
physics.optics