Quantum optical systems of cold atoms, molecules and ions provide one of the best ways to implement quantum information processing tasks, including quantum computing, quantum simulation and quantum communication. The talk starts with a short overview of quantum optical systems with focus on ions and cold atoms. We then discuss our recent work on "open system" quantum simulation and entangled states preparation via quantum reservoir engineering, and discuss related ion experiments. In addition, we give a summary of our present activities in simulating toy models of lattice gauge theories with cold atoms.