Daniel R. Bes made his undergraduate studies at the University of Buenos Aires, UBA, (1950-54), and performed the equivalent of graduate work at the Niels Bohr Institute, NBI, (1956-59), under the advice of A. Bohr and B. Mottelson (Nobel prizes, 1975), on the subject of vibrations in deformed nuclei. Later on Bes became a frequent visitor to the NBI.

Since 1962 he was part in the construction of a first rate Department of Physics at UBA, an experience drastically interrupted in 1966 for political reasons. Subsequently Bes held positions at Carnegie-Mellon University (1967-68) and at the University of Minnesota (1968-71), where he became Full Professor. In 1971 he returned to Argentina, to work at the Comisión Nacional de Energía Atómica, through an appointment from the Consejo Nacional de Investigaciones Científicas y Técnicas (an arrangement from which he presently benefits again). Between 1998-2003 he was Dean of the newly created Facultad de Ingeniería of the Universidad Favaloro. He has been cofounder of the magazine Ciencia Hoy (1989), and President of the Asociación Física Argentina (1994-1998).

Bes has been author/coauthor of more than 120 publications in international physics journals. He has also been interested on topics such as nuclear disarmament and the Latinoamerican debt.

1 Introduction.- 2 Principles of Quantum Mechanics.- 3 The Heisenberg Realization of Quantum Mechanics.- 4 The Schrödinger Realization of Quantum Mechanics.- 5 Angular Momentum.- 6 Three-Dimensional Hamiltonian Problems.- 7 Many-Body Problems.- 8 Approximate Solutions to Quantum Problems.- 9 Time-Dependence in Quantum Mechanics.- 10 Entanglement and Some Recent Applications of Quantum Mechanics.- 11 Measurements and Alternative Interpretations of Quantum Mechanics. Decoherence.- 12 A Brief History of Quantum Mechanics.- 13 Solutions to Problems and Physical Constants.- References.

Starting from basic principles, the book systematically covers both Heisenberg and Schrödinger realizations of quantum mechanics (in this order). It provides excellent didactic introduction to the essential principles and treats recent concepts such as entanglement and decoherence. The book gives the background needed to understand quantum cryptography, teleportation and computation, and it is especially suitable for introducing the spin. This second edition includes a more friendly presentation to Hilbert spaces, and more practical applications e.g. scanning tunneling microscope (potential barrier).