Dr. Moslem Mahdavifar will present his topic, “Quantum Nature of Coherent States” for an AMO seminar.

Abstract: Using quasi-classical (coherent) states from a continuous wave (CW) source, we have been able to observe pure quantum mechanical effects. Our approach is based on the uniform randomization of the temporal phase of these states in an interferometric setting. We call such states as Phased Randomized Coherent States (PRCSs). First, we experimentally realized two-photon bunching and its complementary Hong-Ou-Mandel (HOM) effect. Then, after this quantum signature, we extend the idea to probe the Bell inequality. We successfully observed the violation of CHSH form of the inequality and hence confirmed the existence of entanglement through our approach. In these works, the only degree of freedom involved was polarization. However, we aimed afterwards to add orbital angular momentum (OAM) to this toolbox and examine if we can transfer quantum information using OAM through coherent states from a CW source. Once again, this method correctly matched with theoretical predictions resulting in two-photon bunching experimentally. Therefore, we believe that quasi-classical states can be utilized to a more diverse set of experiments in the domain of quantum optics and quantum information. One main benefit of these states is their photon rate. They do not have any shortage in photon numbers, and thus they do not face scalability problem as much as the other single-photon sources do.