Photon-Atom Interactions

Quang Quy Ho

After researching carefully the well known M. Planck’s law of the black-body radiation, the quantum theory of field and the Einstein’s postulates about interaction of the photon with the atoms, there are a lot of unclear questions about photon and its interaction with atom. From all the above questions, there are three main following questions: Why does the energy of a light mode include zero-point energy? Where does the first photon come from in universe? and What is the first fact as a reason of absorption, emission in the photon-atom interaction? To find out the acceptable answers, here we propose postulates about the zero-photon and then about the new concepts of photon. Using them, we have tried to describe the basic characters of the photon and explain the photon-atom interaction in other way: the spin-spin interaction. Our results showed out the different picture of mechanism of the photon-atom interaction, the existence of the zero-photon energy, the absorption as well as the emission rule and its probabilities.

Julian W. Gardner

L. Camilleri, Guiliano Preparata, J.H. Field +1 more

Michael Werner, Ataç İmamoğlu

Quantum limit of dissipation-free photon-photon interactions at the few photon level is studied in the context of giant Kerr nonlinearities in cavity electromagneti cally induced transparency (EIT). It is shown that photon-photon interaction is largest when the cavity contains a sing le atom. In contrast to conventional nonlinearities, increasing the number of atoms cannot in crease the interaction strength but will in general degrade the performance by enhancing di spersion. In the non-perturbative regime, the single-atom photon-photon interaction can be limited by lossy states excited from long-lived EIT states. Asymptotically, in the strong coupling limit, photon-photon interaction is determined by the single photon-atom coupling strength. Photon blockade occurs for single atoms but only partial blockade can occur for low dispersion and not at all in the high-dispersion limit of the multi-atom case.

Helmut Schwarz

S. Rosenblum, Itay Shomroni, Orel Bechler +3 more

We demonstrate deterministic photon-atom and photon-photon interactions with a single atom coupled to a high-Q fiber-coupled microresonator. Based on Deterministic One Photon Raman Interaction (DOPRI), this scheme can form the basis for all-optical quantum information processing.