Since a new edition of our book has once again become necessary, we have as be fore taken the opportunity to include the latest developments in atomic and quantum physics. These areas continue to yield new and fascinating experimental and theoret ical results which are of fundamental importance and are also extremely interesting to students of science. As a result of newly developed experimental methods and theoretical techniques, it has also become possible to find solutions to some long-es tablished problems. In this spirit we have added an entire new chapter dealing with entangled wavefunctions, the Einstein-Podolsky-Rosen paradox, Bell's inequalities, the paradox of Schrodinger's cat and the concept of decoherence. In addition, we have treated new ideas relating to quantum computers and the numerous quantum physical schemes for constructing them. These new concepts exemplify the rapidly developing area of quantum information. Finally, in this new chapter we have included the experimental realisation of the Bose-Einstein condensation and of the atom laser, which promise important new ap plications. In Chap. 22, "Modern methods of optical spectroscopy", we have added a new section on nondestructive photon detection as an example of efficient methods for investigating the interactions between atoms and photons in resonant cavities. Con sidering the current importance of these areas, we emphasize references to the origi nal literature. These can be found in the Bibliography.