In the excitement and rapid pace of developments, writing pedagogical texts has low priority for most researchers. However, in transforming my lecture l notes into this book, I found a personal benefit: the organization of what I understand in a (hopefully simple) logical sequence. Very little in this text is my original contribution. Most of the knowledge was collected from the research literature. Some was acquired by conversations with colleagues; a kind of physics oral tradition passed between disciples of a similar faith. For many years, diagramatic perturbation theory has been the major theoretical tool for treating interactions in metals, semiconductors, itiner ant magnets, and superconductors. It is in essence a weak coupling expan sion about free quasiparticles. Many experimental discoveries during the last decade, including heavy fermions, fractional quantum Hall effect, high temperature superconductivity, and quantum spin chains, are not readily accessible from the weak coupling point of view. Therefore, recent years have seen vigorous development of alternative, nonperturbative tools for handling strong electron-electron interactions. I concentrate on two basic paradigms of strongly interacting (or con strained) quantum systems: the Hubbard model and the Heisenberg model. These models are vehicles for fundamental concepts, such as effective Ha miltonians, variational ground states, spontaneous symmetry breaking, and quantum disorder. In addition, they are used as test grounds for various nonperturbative approximation schemes that have found applications in diverse areas of theoretical physics.

Non-covalent Interactions in Quantum Chemistry and Physics: Theory and Applications provides an entry point for newcomers and a standard reference for researchers publishing in the area of non-covalent interactions. Written by the leading experts in this field, the book enables experienced researchers to keep up with the most recent developments, emerging methods, and relevant applications. The book gives a comprehensive, in-depth overview of the available quantum-chemistry methods for intermolecular interactions and details the most relevant fields of application for those techniques. Theory and applications are put side-by-side, which allows the reader to gauge the strengths and weaknesses of different computational techniques. Summarizes the state-of-the-art in the computational intermolecular interactions field in a comprehensive work Introduces students and researchers from related fields to the topic of computational non-covalent interactions, providing a single unified source of information Presents the theoretical foundations of current quantum mechanical methods alongside a collection of examples on how they can be applied to solve practical problems

This book constitutes the thoroughly refereed post-conference proceedings of the 5th International Symposium on Quantum Interaction, QI 2011, held in Aberdeen, UK, in June 2011. The 26 revised full papers and 6 revised poster papers, presented together with 1 tutorial and 1 invited talk were carefully reviewed and selected from numerous submissions during two rounds of reviewing and improvement. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, mechanics, social interaction, semantic space and information representation and retrieval.

This volume contains the proceedings of the NSF-CBMS Regional Conference on Topological and Geometric Methods in QFT, held from July 31–August 4, 2017, at Montana State University in Bozeman, Montana. In recent decades, there has been a movement to axiomatize quantum field theory into a mathematical structure. In a different direction, one can ask to test these axiom systems against physics. Can they be used to rederive known facts about quantum theories or, better yet, be the framework in which to solve open problems? Recently, Freed and Hopkins have provided a solution to a classification problem in condensed matter theory, which is ultimately based on the field theory axioms of Graeme Segal. Papers contained in this volume amplify various aspects of the Freed–Hopkins program, develop some category theory, which lies behind the cobordism hypothesis, the major structure theorem for topological field theories, and relate to Costello's approach to perturbative quantum field theory. Two papers on the latter use this framework to recover fundamental results about some physical theories: two-dimensional sigma-models and the bosonic string. Perhaps it is surprising that such sparse axiom systems encode enough structure to prove important results in physics. These successes can be taken as encouragement that the axiom systems are at least on the right track toward articulating what a quantum field theory is.

This book seeks to present a new way of thinking about the interaction of gravitational fields with quantum systems. Despite the massive amounts of research and experimentation, the myriad meetings, seminars and conferences, all of the articles, treatises and books, and the seemingly endless theorization, quantization and just plain speculation that have been engaged in regarding our evolving understanding of the quantum world, that world remains an enigma, even to the experts. The usefulness of general relativity in this regard has proven to be imperfect at best, but there is a new approach. We do not simply have to accept the limitations of Einstein's most celebrated theorem in regard to quantum theory; we can also embrace them, and thereby utilize them, to reveal new facts about the behavior of quantum systems within inertial and gravitational fields, and therefore about the very structure of space–time at the quantum level. By taking existing knowledge of the essential functionality of spin (along with the careful identification of the omnipresent inertial effects) and applying it to the quantum world, the book gives the reader a much clearer picture of the difference between the classical and quantum behaviors of a particle, shows that Einstein's ideas may not be as incompatible within this realm as many have come to believe, sparks new revelations of the way in which gravity affects quantum systems and brings a new level of efficiency—quantum efficiency, if you will—to the study of gravitational theory.

This book constitutes the thoroughly refereed post-conference proceedings of the 10th International Conference on Quantum Interaction, QI 2016, held in San Francisco, CA, USA, in July 2016. The 21 papers presented in this book were carefully reviewed and selected from 39 submissions. The papers address topics such as: Fundamentals; Quantum Cognition; Language and Applications; Contextuality and Foundations of Probability; and Quantum-Like Measurements.

This book constitutes the thoroughly refereed post-conference proceedings of the 10th International Conference on Quantum Interaction, QI 2018, held in Nice, France, in September 2018. The 12 papers presented in this book were carefully reviewed and selected from 15 submissions. The papers address topics such as: psychology, economics, semantic and memory, natural language processing, cognition, information retrieval, biology, and political science.