This accessible and self-contained text presents the essential theoretical techniques developed to describe quantum processes, alongside a detailed review of the devices and experimental methods required in quantum measurement.Ideal for advanced undergraduate and graduate students seeking to extend their knowledge of the physics underlying quantum technologies, the book develops a thorough understanding of quantum measurement theory, quantum processes and the evolution of quantum states.A wide range of basic quantum systems are discussed, including atoms, ions, photons, and more complex macroscopic quantum devices such as opto-mechanical systems and superconducting circuits.Quantum phenomena are also covered in detail, from entanglement and quantum jumps, to quantum fluctuations in optical systems.Numerous problems at the end of each chapter problems enable the reader to consolidate key theoretical concepts and to develop their understanding of the most widely-used experimental techniques.