Illustrating the differences between a Superposition and a Mixture of States

This experiment is a quantum eraser experiment that makes use of a path type entanglement. Since pairs of photons are generated, the goal is to generate a double-slit interference pattern from one half of a momentum entangled photon ensemble by performing a local transformation on the other, and subsequently detecting the entangled pairs. A classical system was also prepared to mimic the quantum entangled system where we did not have entangled photons and the two paths were attenuated to a single photon level. It was found that in a mixture, unlike a superposition, there is no way to erase the which-slit information and generate a double-slit interference pattern.