Modern Quantum Theory

Aimed at university students, as well as academic and industry researchers, this textbook is an introduction to quantum theory, covering the development of the field from the early stages of quantum mechanics to modern quantum information, with a focus on entanglement theory.

A comprehensive and engaging textbook, providing a graduate-level, non-historical, modern introduction of quantum mechanical concepts.

A substantial update of this award-winning and highly regarded cosmology textbook, for advanced undergraduates in physics and astronomy.

Over the course of the past two to three decades, new tools of presentation and mathematical treatment have emerged and the subject matter of quantum mechanics has gone through significant changes. A Textbook on Modern Quantum Mechanics presents the selected elementary, intermediate, and advance topics with rejuvenated approach to the subject matter. Newly merged topics from contemporary physics and chemistry are included in the text as well as solved examples. The book covers: (i) fundamental discoveries that are the foundation of modern quantum mechanics; (ii) solution of Schrödinger’s wave equation for 1D problems and their importance; (iii) matrix and vector formulation of quantum mechanics; (iv) transformations, symmetries, and conservation laws; (v) angular and spin momenta; (vi) solution of Schrödinger equation for central potentials; (vii) time-independent perturbation theory, variational method and WKB approximation; (viii) quantum theory of scattering; (xi) many-particle systems and their quantum mechanical treatments; (x) time-dependent perturbations and the interaction of fields with matter; (xi) relativistic quantum mechanics; and (xii) quantization of fields and the second quantization. Key Features: It provides everything a student needs to know for succeeding at all levels of the undergraduate and graduate studies. It covers most of the topics that are taught under (a) elementary, (b) intermediate, and (c) advance courses of quantum mechanics at universities and colleges. It has detailed and elegant mathematical treatment with contemporary style of interpretation and presentation in simple English. Solved examples and unsolved exercises that are part of each chapter to consolidate the readers' understanding of fundamental concepts. The subject matter of the book is well tested on the students taught by the author over a period of 30 years. This is a valuable textbook for students pursuing Bachelor of Science, Master of Science, and Doctor of Philosophy (PhD) degrees in the subjects of Physics, Chemistry, and materials science in India, South Asian countries, the United States, and Europe.

This graduate-level text explains the modern in-depth approaches to the calculation of electronic structure and the properties of molecules. Largely self-contained, it features more than 150 exercises. 1989 edition.

In the last few decades quantum theory has experienced an extensive revival owing to the rapid development of quantum information and quantum technologies. Based on a series of courses taught by the authors, the book takes the reader on a journey from the beginnings of quantum theory in the early twentieth century to the realm of quantum-information processing in the twenty-first. The central aim of this textbook, therefore, is to offer a detailed introduction to quantum theory that covers both physical and information-theoretic aspects, with a particular focus on the concept of entanglement and its characteristics, variants, and applications. Suitable for undergraduate students in physics and related subjects who encounter quantum mechanics for the first time, this book also serves as a resource for graduate students who want to engage with more advanced topics, offering a collection of derivations, proofs, technical methods, and references for graduate students and more experienced readers engaged with teaching and active research. The book is divided into three parts: Part I - Quantum Mechanics, Part II - Entanglement and Non-Locality, and Part III - Advanced Topics in Modern Quantum Physics. Part I provides a modern view on quantum mechanics, a central topic of theoretical physics. Part II is dedicated to the foundations of quantum mechanics and entanglement: starting with density operators, hidden-variable theories, the Einstein-Podolsky-Rosen Paradox, and Bell Inequalities, but also touching upon philosophical questions, followed by a deeper study of entanglement-based quantum communication protocols like teleportation, before giving a detailed exposition of entanglement theory, including tools for the detection and quantification of entanglement. Part III is intended as a collection of standalone chapters to supplement the contents of Parts I and II, covering more advanced topics such as classical and quantum entropies, quantum operations and measurements, decoherence, quantum metrology and quantum optics, and entanglement in particle physics.

This book discusses the physical and mathematical foundations of modern quantum mechanics and three realistic quantum theories that John Stuart Bell called "theories without observers" because they do not merely speak about measurements but develop an objective picture of the physical world. These are Bohmian mechanics, the GRW collapse theory, and the Many Worlds theory. The book is ideal to accompany or supplement a lecture course on quantum mechanics, but also suited for self-study, particularly for those who have completed such a course but are left puzzled by the question: "What does the mathematical formalism, which I have so laboriously learned and applied, actually tell us about nature?”

Quantum Theory: Density, Condensation, and Bonding presents in a unitary manner the main actual theories of matter, mainly the density function theory (DFT) for fermions, the Bose-Einstein condensation (BEC) for bosons, and chemical bonding as a special realization of the first two so-called mixed fermionic-bosonic states. The book covers the modern and ultimately developed quantum theories involving the key concepts of density, condensation, and bonding. The book compiles, for the first time, the density functional theory with Bose-Einstein condensation and chemical bonding theories in a fresh and novel perspective. The book introduces modern theories of matter structure and explains the nature of chemical bonds under the consecrated and ultimate quantum paradigms of molecular structure. The book is divided into three parts, one for each level of studies: Part I: Primer Density Functional Theory is suitable for undergraduate introductory courses in physics, chemistry, and the natural sciences. Part II: Primer Density Functional Bose-Einstein Condensation Theory would be suitable for graduate- or master-level courses in physics or natural sciences. Part III: Modern Quantum Theories of Chemical Bonding is written for the post-graduate, master or doctorate courses on quantum structure of molecules in chemistry or natural sciences. Thus, this book is organized as a succession of three linked courses, from undergraduate, to graduate, to postgraduate levels in modern quantum theories of many-body systems. It covers three main concepts: density, condensation, and bonding and contains the most celebrated and challenging theories of matter. The book provides a fresh perspective on the quantum theory of structure of physico-chemical systems and will show students at all levels and researchers the way for future elaboration and discoveries toward the unification of the physical and chemical concepts of matter.