Experimental two-photon, three-dimensional entanglement for quantum communication

Phys Rev Lett. 2002 Dec 9;89(24):240401. doi: 10.1103/PhysRevLett.89.240401. Epub 2002 Nov 20.


Orbital angular momentum entangled photons emitted by a down-conversion source are in higher dimensional entangled states. Here we report the experimental confirmation by demonstrating a violation of a generalized Clauser-Horne-Shimony-Holt-type Bell inequality in three dimensions by more than 18 standard deviations. Higher dimensional entangled states allow the realization of new types of quantum communication protocols. They also provide a more secure quantum cryptography scheme. Therefore our experimental results are likely to have applications in future quantum communication technology.