Correcting Phase in a Bell’s Inequality Measurement

Bell’s Inequality defines a limit that is imposed on all hidden variable theories. The expressions that are associated with the inequality are evaluated through measurements of the correlation of an entangled property of two objects. Quantum theory predicts that under certain conditions Bell’s Inequality is violated. A set of paired Beta Barium Borate (BBO) crystals was used to down convert a photon into a pair of photons with entangled linear polarizations. During the down conversion, a relative phase shift is introduced between the down converted photons in the quantum state. The quantum model does not violate Bell’s Inequality for some values of the phase shift. An investigation was conducted on the effect of wave plates on perpendicular linear polarizations. A model of phase shift between perpendicular linear polarization as a function of orientation of a wave plate was derived. Then polarizers and a laser power meter were used to test the model. Finding agreement between the model and test results, a wave plate was then used to correct the phase shift in the quantum state. A measurement was then made that violated Bell’s Inequality, which is consistent with quantum theory.