Quantum information has become an independent fast growing research eld. There are new departments and labs all around the world, devoted to particular or even complex studies of mathematics, physics, and technology of controlling quantum degrees of freedom. The promised advantage of quantum technologies has ob- ously electri ed the eld which had been considered a bit marginal until quite - cently. Before, many foundational quantum features had never been tested or used on single quantum systems but on ensembles of them. Illustrations of reduction, - cay, or recurrence of quantum superposition on single states went to the pages of regular text-books, without being experimentally tested ever. Nowadays, however, a youngest generation of specialists has imbibed quantum theoretical and experim- tal foundations “from infancy”. From 2001 on, in spring semesters I gave special courses for under- and po- graduate physicists at Eötvös University. The twelve lectures could not include all standard chapters of quantum information. My guiding principles were those of the theoretical physicist and the believer in the unity of physics. I achieved a decent b- ance between the core text of quantum information and the chapters that link it to the edi ce of theoretical physics. Scholarly experience of the passed ve semesters will be utilized in this book.weiterlesen