The quantum measurement problem is one of the most fascinating and challenging topics in physics both theoretically and experimentally. It involves deep questions and the use of very sophisticated and elegant techniques. After analyzing the fundamental principles of quantum mechanics and of the Copenhagen interpretation, this book reviews the most important approaches to the measurement problem and rigorously reformulates the "collapse of the wave function" by measurement, as a dephasing process quantitatively characterized by an order parameter (called the decoherence parameter), according to the many-Hilbert-space approach to the problem.The book deals not only with the measurement processes (including imperfect measurements) but also with related interference and mesoscopic phenomena - by means of general arguments - of solvable models and of numerical simulations. The quantum Zeno effect and the issue of irreversibility are also discussed.

QUANTUMCOMM 2009--the International Conference on Quantum Communi- tion and Quantum Networking (from satellite to nanoscale)--took place in Vico Equense near Naples, Italy, during October 26-30, 2009. The conference made a significant step toward stimulating direct dialogue between the communities of quantum physics and quantum information researchers who work with photons, atoms, and electrons in pursuit of the common goal of investigating and utilizing the transfer of physical information between quantum systems. This meeting brought together experts in quantum communication, quantum inf- mation processing, quantum nanoscale physics, quantum photonics, and networking. In the light of traditional approaches to quantum information processing, quantum communication mainly deals with encoding and securely distributing quantum states of light in optical fiber or in free space in order to provide the technical means for quantum cryptography applications. Exciting advances in the area of quantum c- munication over the last decade have made the metropolitan quantum network a re- ity. Several papers presented at this meeting have demonstrated that quantum crypt- raphy is approaching the point of becoming a high-tech application rather than a - search subject. The natural distance limitation of quantum cryptography has been significantly augmented using ideas of global quantum communication with stab- orbit satellites. The results presented at this conference demonstrated that practical secure satellite communication is clearly within reach.