The field of quantum optics has progressed rapidly in the last twenty five years with the advent of the laser. Over much of this period the phenomena studied could be described adequately by semiclassical treatments. Quite recently however, there has been a revival of interest in genuinely quantum mechanical effects. The Malvern Symposium of December 1985 brought together world experts for a meeting which concentrated largely on these quantum effects. The presentations in this unique meeting combine review material with the very latest results and so will be of value to students of quantum optics and measurement theory at all levels. The first articles cover the exciting topic of the generation of squeezed states of light in the laboratory, and their possible uses. Experimental success has been long sought and very recently attained. The reader will find presented the state of the art in this field. Next to lasing itself, optical bistability has been the most widely studied phenomenon in quantum optics, largely for its technological promise. However, it also provides a fundamental system to study quuantum effects. Recent theoretical studies of optical bistability with small numbers of atoms are surveyed. In such situations quantum features such as antibunching become significant, and the articles in this volume should be a guide to those venturing into this challenging area. In other articles discussions of fluctuations from other noise sources and instabilities in optical bistabilty are presented in a clear and interesting way. Perhaps the least classical state on quantum optics is that describing a single photon. Recent experiments which produce such states are reviewed. A theoretical review of the photon together with some new material is given which delves deeply into relativistic quantum field theory in order to describe the concept of weakly localised photon states. The material here is very rarely presented in the context of quantum optics. The history of the theory of the quantum fluctuations in a laser is then reviewed. An off-shoot of this theory is the study of quantum chaos in dissipative systems and recent results in this new area are given in a succeeding article. There are further stimulating articles on Rydberg atom systems and quantum electrodynamics. The volume ends with an entertaining and incisive study of quantum measurement problems, such as the Schrodinger cat papadox, using concepts and measuring devices found in quantum optics. other_titles

The Industrial Revolution meets the quantum-technology revolution! A steampunk adventure guide to how mind-blowing quantum physics is transforming our understanding of information and energy. Victorian era steam engines and particle physics may seem worlds (as well as centuries) apart, yet a new branch of science, quantum thermodynamics, reenvisions the scientific underpinnings of the Industrial Revolution through the lens of today's roaring quantum information revolution. Classical thermodynamics, understood as the study of engines, energy, and efficiency, needs reimagining to take advantage of quantum mechanics, the basic framework that explores the nature of reality by peering at minute matters, down to the momentum of a single particle. In her exciting new book, intrepid Harvard-trained physicist Dr. Nicole Yunger Halpern introduces these concepts to the uninitiated with what she calls "quantum steampunk," after the fantastical genre that pairs futuristic technologies with Victorian sensibilities. While readers follow the adventures of a rag-tag steampunk crew on trains, dirigibles, and automobiles, they explore questions such as, "Can quantum physics revolutionize engines?" and "What deeper secrets can quantum information reveal about the trajectory of time?" Yunger Halpern also describes her own adventures in the quantum universe and provides an insider's look at the work of the scientists obsessed with its technological promise. Moving from fundamental physics to cutting-edge experimental applications, Quantum Steampunk explores the field's aesthetic, shares its whimsy, and gazes into the potential of a quantum future. The result is a blast for fans of science, science fiction, and fantasy.

Quantum Computing is an ever-increasing field of interest both from a conceptual and applied standpoint. Quantum Computing, belonging to the so called "Quantum Information Science", is founded on the principles of Quantum Mechanics and Information Science. Quantum Mechanics has radically changed our vision and understanding of the physical reality and has had also an enormous technological and societal impact. On the other hand, the developing of Information Theory, including computer science and communications theory, made possible the information "revolution" which had a deep impact on our everyday life. Quantum Computing then relates to the possibility to represent, process and manipulate information by using the principles of quantum mechanics. Apart the theoretical importance of quantum computing to further understand the quantum mechanical behavior of physical systems and the physical foundation of information itself at the most elementary level, probably the most interesting feature of Quantum Computing is related to the possibility to design and realize an actual quantum computer which processes information in the form of quantum-bits or qubits. The great interest of scientific community in the realization of such devices mainly concerns the common believe they could be enormously faster than their classical counterparts so allowing their employment in all the applied fields where computational power is a key feature. Furthermore, the study of Quantum Computing, both at the physical and computational level, would be very important for a deeper understanding of the quantum behavior of a very wide range of physical systems including condensed matter, living systems, elementary particles, astrophysical structures and so on. Despite the general theoretical basis of quantum computing are sufficiently understood, the actual realization of a general - purpose and really usable quantum computer has posed great difficulties so far, mainly related to the issue of "quantum decoherence", the computational speed and scalability many of which still remain substantially unsolved. This volume doesn't mean to represent a complete or a beginner guide to Quantum Computing but has the aim to present some of its most interesting and fascinating developments in different frontier areas related to both theoretical and applied aspects, such, for example, the possibility to realize a quantum superfast "hypercomputing" system using water molecules as physical substrate to process, storage and retrieve information; the connection between quantum computers and quantum gravity; the development of an "instantaneous quantum computer algorithm"; the realization of a universal quantum computer, of a brain-like quantum supercomputer and many others frontiers topics. The target audience of this book is then composed by scientists and researchers interested in the most advanced theoretical and applied developments of quantum computation and quantum information.

This volume brings together leading quantum physicists to expound on the meaning and future directions of quantum mechanics. It offers new insights from different vantage points to tackle essential questions in quantum mechanics and its interpretation. All the authors have written for a broad readership, and the resulting volume will appeal to everyone wishing to keep abreast of new developments in quantum mechanics, as well as its history and philosophy.

Entanglement was initially thought by some to be an oddity restricted to the realm of thought experiments. However, Bell’s inequality delimiting local - havior and the experimental demonstration of its violation more than 25 years ago made it entirely clear that non-local properties of pure quantum states are more than an intellectual curiosity. Entanglement and non-locality are now understood to ?gure prominently in the microphysical world, a realm into which technology is rapidly hurtling. Information theory is also increasingly recognized by physicists and philosophers as intimately related to the foun- tions of mechanics. The clearest indicator of this relationship is that between quantum information and entanglement. To some degree, a deep relationship between information and mechanics in the quantum context was already there to be seen upon the introduction by Max Born and Wolfgang Pauli of the idea that the essence of pure quantum states lies in their provision of probabilities regarding the behavior of quantum systems, via what has come to be known as the Born rule. The signi?cance of the relationship between mechanics and information became even clearer with Leo Szilard’s analysis of James Clerk Maxwell’s infamous demon thought experiment. Here, in addition to examining both entanglement and quantum infor- tion and their relationship, I endeavor to critically assess the in?uence of the study of these subjects on the interpretation of quantum theory.

Quantum mechanics is one of mankind's most remarkable intellectual achievements. Stunningly successful and elegant, it challenges our deepest intuitions about the world. In this book, seventeen physicists and philosophers, all deeply concerned with understanding quantum mechanics, reply to Schlosshauer's penetrating questions about the central issues. They grant us an intimate look at their radically different ways of making sense of the theory's strangeness. What is quantum mechanics about? What is it telling us about nature? Can quantum information or new experiments help lift the fog? And where are we headed next? Everyone interested in the contemporary but often longstanding conundrums of quantum theory, whether lay reader or expert, will find much food for thought in these pages. A wealth of personal reflections and anecdotes guarantee an engaging read. Participants: Guido Bacciagaluppi, Caslav Brukner, Jeffrey Bub, Arthur Fine, Christopher Fuchs, GianCarlo Ghirardi, Shelly Goldstein, Daniel Greenberger, Lucien Hardy, Anthony Leggett, Tim Maudlin, David Mermin, Lee Smolin, Antony Valentini, David Wallace, Anton Zeilinger, and Wojciech Zurek.