Quantum information processing, a vibrant field of research at the intersection of physics, mathematics and computer science, has seen tremendous progress over the last couple of years, both with respect to the experimental realization of stable qubits (the quantum analog to bits in conventional computing) and the fundamental understanding, development and implementation of quantum-based algorithms. Consequently, proof-of-concept studies have unambiguously shown that quantum computers are possible and have the potential to dramatically exceed the capabilities of today's conventional computers.   This comprehensive handbook on the rapidly advancing field presents the foundations of quantum information, taking into account the current state of research and development, and the emerging and already realized applications in quantum technology. It thus covers all current concepts in quantum computing, both theoretical and experimental, before moving on to the latest implementations of quantum computing and communication protocols. It is a must-have for experimental and theoretical physicists in academia and industry as well as for materials scientists, engineers and computer scientists who work in the field of quantum information.