Recent experiments in quantum optics and their implications - I

We discuss novel quantum effects pertaining to single atoms and/or photons in the recently developed state-of-the-art experiments with ion traps and microwave/optical cavities cooled to very low temperatures. These experiments are important from the point of view of fundamental physics as well as due to the growing field of quantum information/computation. In the first part of the article, we mainly concentrate on the experiments in ion traps such as observation of quantum jumps along with the underlying theory. We have also discussed non-classical nature of light, quantum Zeno effect and interaction free measurement.