The subject of this book is based on the compulsory course "Quantum Optics and Lasers" of the Department of "Solid State Physics" of the Faculty of Physics of the Natural Sciences School of the National and Kapodistrian University of Athens. 1. Introduction to the quantum nature of light. 2. Mechanisms of interaction of electromagnetic (EM) radiation and matter (two-level system). 3. Semiclassical approach of the interaction of EM radiation and matter. EM field: classically. Two-level system e.g. atom: quantum mechanically. 4. Quantum mechanical approach of the interaction of EM radiation and matter. EM field quantization. 5. Lasers. 6. Density matrix. 7. Some other issues for the properties and the operation of Lasers.
Since the beginning of scientific inquiry the nature of light has played a vital role in our understanding of the physical world. Physicists have marveled at the dual nature of light as both corpuscle and wave; we have harnessed the remarkable coherent properties of light through the use of lasers; and the quantum mechanics of the interaction of photons with matter continue to provide fascinating avenues of basic research. In essence, any alteration of electromagnetism, the fundamental interaction overning atomic, molecular and condensed matter physics, will lead to fundamentally new phenomena in all these areas.