Fundamental atom-field interaction is the building block of all optical phenomena ranging from single atom in a cavity to nonlinear optical interactions in condensed matter. Of particular interest are the nonclassical photon statistics in the cavity-quantum-electrodynamics, single atom trapping and its applications to quantum information, and quantum chaos phenomena in deformed microcavities. In addition, principles and techniques are investigated for submicron-resolution three-dimensional imaging of semi-transparent samples based on nonlinear optics, along with wave and ray optics applications to imaging systems. Nowadays, modern experimental techniques can trap atoms very quietly, which means at a very low temperature (~100 nK). In this way, the Bose-Einstein conjecture of the condensed macroscopic quantum state can be revealed and studied unambiguously. In addition, theoretical studies on foundations of quantum mechanics, quantum information theory, and nonclassical properties of light are actively carried out.
