Quantum Processes And Measurement

Based on the Fourth International Conference on Quantum Communication, Measurement and Computing, this volume brings together scientists working in the interdisciplinary fields of quantum communication science and technology. In contrast to the previous conferences in this series, which were mainly theoretical, QCH '98 devoted more attention to the experimental aspects. Topics include quantum information theory, quantum computing, quantum communication systems, cryptography, new quantum effects and their experiments, generation and detection of nonclassical light, quantum noise, stochastic processes and filtering, and quantum measurement theory.

In last years increasing attention has been again devoted to interpretations of quantum theory. In the same time interesting quantum optical experiments have been performed using nonlinear optical processes, in particular frequency down conversion, which provided new information about nature of a photon on the basis of interference and correlation (coincidence) phenomena. Such single-photon and twin-photon effects of quantum optics provide new point of view of interpretations of quantum theory and new tests of its principles. The purpose of this book is to discuss these questions. To follow this goal we give brief reviews of principles of quantum theory and of quantum theory of measurement. As a fundamental theoretical tool the coherent state technique is adopted based on a general algebraic treatment, including the de­ scription of interaction of radiation and matter. Typical quantum behaviour of physical systems is exhibited by nonclassical optical phenomena, which can be examined using photon interferences and correlations.

This book shows how Bohmian mechanics overcomes the need for a measurement postulate involving wave function collapse. The measuring process plays a very important role in quantum mechanics. It has been widely analyzed within the Copenhagen approach through the Born and von Neumann postulates,