Our ability to engineer quantum states of light and matter has significantly advanced over the past two decades fostering future quantum technologies including quantum optical communication, quantum sensing as well as quantum computation. The strong nonlinear light-atom interaction is the key to deterministic quantum state preparation and quantum photonic processing. One route to enhancing the usually weak nonlinear light-atom interactions is to approach the regime of cavity quantum electrodynamics (cQED) interaction by means of high quality optical resonators. I describe light-atom interactions in the weak and strong QED regime and show how such coherent interactions can be used to implement quantum storage, logic operations, and state engineering for optical information. Moreover, I present our ongoing effort at Purdue to realize quantum phenomena at the single photon level using chip-scale photonic systems.