This book is a collection of articles on the contemporary status of Quantum Mechanics dedicated to the fundamental issues of entanglement, decoherence, irreversibility, information processing, and control of quantum evolution, with a view of possible applications. It has multidisciplinary character and is addressed at a broad readership in physics, computer science, chemistry, and electrical engineering. It is written by the world-leading experts in pertinent fields such as Quantum Computing, Atomic, Molecular and Optical Physics, Condensed Matter Physics, and Statistical Physics.