Elements of Quantum Optics gives a broad coverage of the basic elements necessary to understanding and researching laser physics and quantum optics. It presents a variety of theoretical tools and important results for two-level and semiconductor media, many of which could only be found in the original literature or in specialized monographs up to now. The text reveals the close connection between many seemingly unrelated topics, such as probe absorption, four-wave mixing, optical instabilities, and resonance fluorescence and squeezing. This third edition includes new chapters on atom optics and cavity quantum electrodynamics, and an expanded discussion of quantum mechanics, system-reservoir interactions and second quantization.