The ultimate introduction, textbook, and reference on decoherence and the quantum-to-classical transition. This detailed but accessible text describes the concepts, formalism, interpretation, and experimental observation of decoherence and explains how decoherence is responsible for the emergence, from the realm of quantum mechanics, of the classical world of our experience. Topics include: • Foundational problems at the quantum–classical border; • The role of the environment and entanglement; • Environment-induced loss of coherence and superselection; • Scattering-induced decoherence and spatial localization; • Master equations; • Decoherence models; • Experimental realization of "Schrödinger kittens" and their decoherence; • Quantum computing, quantum error correction, and decoherence-free subspaces; • Implications of decoherence for interpretations of quantum mechanics and for the "measurement problem"; • Decoherence in the brain. Written in a lucid and concise style that is accessible to all readers with a basic knowledge of quantum mechanics, this stimulating book tells the "classical from quantum" story in a comprehensive and coherent manner that brings together the foundational, technical, and experimental aspects of decoherence. It will be an indispensable resource for newcomers and experts alike. "Reads like a bestseller. An engaging and intuitive treatment of a very important subject, combining the scope of a monograph with the clarity of a textbook and the intellectual excitement of a Sherlock Holmes adventure." Wojciech Zurek, Los Alamos "Everyone who works in the borderlands between quantum and classical physics, from philosophers of physics to quantum-computer technologists, will find much here to stimulate and inspire." Gerard Milburn, University of Queensland "A thorough, readable, and very useful account of decoherence theory and its diverse applications. Valuable as a text and as a reference work, both for graduate students and for active researchers in the field." Steve Adler, IAS, Princeton .