Entangled states are important for quantum cryptography, being used in several protocols of quantum key distribution. These provide an alternative to single-photon-based protocols. Entangled states are also important in fundamental terms, in the way that the behavior of these states is contradictory with the predicted by local theories. This contradiction is shown by the violation of Bell’s inequalities, as the inequality proposed by Clauser, Horne, Shimony and Holt (CHSH). In this work [1] we shown the violation of CHSH inequality using
two-particle states. We discussed pure states, an arbitrary state, and the Greenberger-Horne-Zeilinger (GHZ) state. Using the spontaneous four-wave mixing process we generated entangled photon pairs in a highly non-linear fiber, and experimentally verified the violation of CHSH inequality.