Kvantefysik (kvantemekanik og kvantefeltteori)

Quantennetzwerke ermöglichen ähnlich wie klassische Kommunikationsnetzwerke, wie zum Beispiel das Internet, eine Verbindung zwischen potentiell weit entfernten Nutzern. Zu diesem Zweck werden verschränkte Quantenzustände über die einzelnen Verbindungen verteilt und können beispielsweise zur beweisbar sicheren Kommunikation mittels Quantenkryptographie genutzt werden. Quantennetzwerke bestehen aus vielen verschiedenen probabilistischen Bausteinen: Sowohl die Erzeugung verschränkter Zustände als auch deren Übertragung zwischen unterschiedlichen Netzwerkknoten und die Verbindung benachbarter Links entsprechen unterschiedlichen stochastischen Prozessen. In dem vorliegenden Buch werden verschiedene Modellierungsmöglichkeiten dieser Prozesse vorgestellt und verglichen. Das Ziel ist dabei jeweils die Berechnung der Wartezeit bis zur Erzeugung einer Ende-zu-Ende-Verbindung zwischen den Kommunikationspartnern.

This book covers recent developments in the understanding, quantification, and exploitation of entanglement in spin chain models from both condensed matter and quantum information perspectives. Spin chain models are at the foundation of condensed matter physics and quantum information technologies and elucidate many fundamental phenomena such as information scrambling, quantum phase transitions, and many-body localization. Moreover, many quantum materials and emerging quantum devices are well described by spin chains. Comprising accessible, self-contained chapters written by leading researchers, this book is essential reading for graduate students and researchers in quantum materials and quantum information.  The coverage is comprehensive, from the fundamental entanglement aspects of quantum criticality, non-equilibrium dynamics, classical and quantum simulation of spin chains through to their experimental realizations, and beyond into machine learning applications.

This book introduces the basic concept of a dissipative soliton, before going to explore recent theoretical and experimental results for various classes of dissipative optical solitons, high-energy dissipative solitons and their applications, and mode-locked fiber lasers.A soliton is a concept which describes various physical phenomena ranging from solitary waves forming on water to ultrashort optical pulses propagating in an optical fiber. While solitons are usually attributed to integrability, in recent years the notion of a soliton has been extended to various systems which are not necessarily integrable.  Until now, the main emphasis has been given to well-known conservative soliton systems, but new avenues of inquiry were opened when physicists realized that solitary waves did indeed exist in a wide range of non-integrable and non-conservative systems leading to the concept of so-called dissipative optical solitons.Dissipative optical solitons have many unique properties which differ from those of their conservative counterparts. For example, except for very few cases, they form zero-parameter families and their properties are completely determined by the external parameters of the optical system. They can exist indefinitely in time, as long as these parameters stay constant. These features of dissipative solitons are highly desirable for several applications, such as in-line regeneration of optical data streams and generation of stable trains of laser pulses by mode-locked cavities.

This textbook presents the fundamental concepts and theories in solid-state engineering physics in a very simple, systematic, and comprehensive way. The book is written in a lucid manner so that students are able to understand the realization behind the mathematical concepts which are the backbone of this subject. All the subject fundamentals and related derivations are discussed in an easy and comprehensive way to make the students strong about the basics of the solid-state engineering physics. The philosophy of presentation and material content in the book are based on concept-based approach toward the subject. The key features also lie in the solutions of several interesting numerical problems so that the students should have the idea of the practical usages of the subject. The book will benefit students who are taking introductory courses in solid-state physics for engineering.

This dissertation addresses the question of how energy is conserved in quantum measurement. This question is significant for a number of reasons: the conventional way of expressing conservation laws pertains only to isolated systems (whereasmeasurement always involves coupling to an external apparatus), the superposition principle implies that the energy of a quantum system may be poorly defined before and/or after a measurement, and measurements can affect the energy of a quantum system(either increasing or decreasing it on average).

This book presents proceedings from the XXIV DAE-BRNS High Energy Physics (HEP) Symposium 2020, held at the National Institute of Science Education and Research, Jatni, Odisha, India. The contributions cover a variety of topics in particle physics, astroparticle physics, cosmology and related areas from both experimental and theoretical perspectives, namely (1) Standard Model Physics, (2) Beyond Standard Model Physics, (3) Relativistic Heavy-Ion Physics & QCD, (4) Neutrino Physics, (5) Particle Astrophysics & Cosmology, (6) Detector Development Future Facilities and Experiments, (7) Formal Theory, (8) Societal Applications: Medical Physics, Imaging, etc.

Learn to write algorithms and program in the new field of quantum computing. This second edition is updated to equip you with the latest knowledge and tools needed to be a complex problem-solver in this ever-evolving landscape. The book has expanded its coverage of current and future advancements and investments by IT companies in this emerging technology. Most chapters are thoroughly revised to incorporate the latest updates to IBM Quantum's systems and offerings, such as improved algorithms, integrating hardware advancements, software enhancements, bug fixes, and more. Yoüll examine quantum computing in the cloud and run experiments there on a real quantum device. Along the way yoüll cover game theory with the Magic Square, an example of quantum pseudo-telepathy. Yoüll also learn to write code using QISKit, Python SDK, and other APIs such as QASM and execute it against simulators (local or remote) or a real quantum computer. Then peek inside the inner workings of the Bell states for entanglement, Grover¿s algorithm for linear search, Shor¿s algorithm for integer factorization, and other algorithms in the fields of optimization, and more. Finally, yoüll learn the current quantum algorithms for entanglement, random number generation, linear search, integer factorization, and others. By the end of this book, yoüll understand how quantum computing provides massive parallelism and significant computational speedups over classical computersWhat You'll LearnWrite algorithms that provide superior performance over their classical counterpartsCreate a quantum number generator: the quintessential coin flip with a quantum twistExamine the quantum algorithms in use today for random number generation, linear search, and moreDiscover quantum teleportationHandle the counterfeit coin problem, a classic puzzle Put your knowledge to the testwith more than 150 practice exercises Who This Book Is ForDevelopers, programmers, computer science researchers, teachers, and students.

With a rare blend of scientific insight and writing as graceful as the theories it so deftly explains, The Elegant Universe remains the unrivaled account of the modern search for the deepest laws of nature: "a standard that will be hard to beat" (George Johnson, New York Times Book Review). In this new 25th anniversary edition, renowned physicist and author Brian Greene-"the single best explainer of abstruse concepts in the world today" (Washington Post)-updates his classic work with a new preface and epilogue summarizing the significant theoretical and experimental developments over the past quarter-century. From established science, including relativity and quantum mechanics, to the cutting edge of thinking on black holes, string theory, and quantum gravity, The Elegant Universe makes some of the most sophisticated concepts ever contemplated thoroughly accessible and entertaining, bringing us closer than ever to comprehending how the universe works.

"Quantum field theory is how modern physics describes nature at its most profound level. Starting with the basics of quantum mechanics itself, Sean Carroll explains measurement and entanglement before explaining how the world is really made of fields. You will finally understand why matter is solid, why there is antimatter, where the sizes of atoms come from, and why the predictions of quantum field theory are so ... successful. Fundamental ideas like spin, symmetry, Feynman diagrams, and the Higgs mechanism are explained for real, not just through amusing stories. Beyond Newton, beyond Einstein, and all the intuitive notions that have guided homo sapiens for millennia, this book is a journey to a once unimaginable truth about what our universe is"--

This thesis makes significant advances towards an understanding of superconductivity in the cuprate family of unconventional, high-temperature superconductors. Even though the high-temperature superconductors were discovered over 35 years ago, there is not yet a general consensus on an acceptable theory of superconductivity in these materials. One of the early proposals suggested that collective magnetic excitations of the conduction electrons could lead them to form pairs, which in turn condense to form the superconducting state at a critical temperature Tc. Quantitative calculations of Tc using experimental data were, however, not available to verify the applicability of this magnetic mechanism. In this thesis, the author constructed an angle-resolved photoemission apparatus that could provide sufficiently accurate data of the electronic excitation spectra of samples in the normal state, data which was furthermore unusually devoid of any surface contamination. The author also applied the Bethe-Salpeter method to his uncommonly pristine and precise normal state data, and was able to predict the approximate superconducting transition temperatures of different samples. This rare combination of experiment with sophisticated theoretical calculations leads to the conclusion that antiferromagnetic correlations are a viable candidate for the pairing interaction in the cuprate superconductors.

"The best-selling author of The God Equation turns his attention to humanity's next great technological advancement--quantum computing, which could change every aspect of our daily lives by solving some of our greatest challenges, from climate change to world hunger to incurable diseases"--

'If you want to remember why you once fell in love with the idea of the cosmos, or want to fall in love with it for the first time, then this book is for you' ObserverFrom Carlo Rovelli, the bestselling author of Seven Brief Lessons on Physics, this is a story of wonder, new worlds and why the end is just the beginningLet us journey into the heart of a black hole. Let us slip beyond its boundary, the horizon, and tumble - on and on - down this crack in the universe. As we plunge, we'll see geometry fold, we'll feel the equations draw tight around us. Eventually, we'll pass it: the remains of a star, deep and dense and falling further far. And then - the bottom. Where time and space end, and the white hole is born . . .With lightness and magic, here Carlo Rovelli traces the ongoing adventure of his own cutting-edge research, of the uncertainty and joy of going where we've not yet been. Guiding us to the edge of theory and experiment, he invites us to go beyond, to experience the fever and the disquiet of science. Here is the extraordinary life of a white hole.A BOOK OF THE YEAR ACCORDING TO THE FINANCIAL TIMES * SUNDAY TELEGRAPH * NEW STATESMAN * NEW SCIENTIST

Quantum mechanics is an extraordinarily successful scientific theory. It is also completely baffling. From the moment of its inception, its founders struggled to understand its meaning. This struggle was most famously encapsulated in the debate between Niels Bohr and Albert Einstein; Quantum Drama tells the story of their engagement and its legacy.

Schon früh im Physikstudium und auch bereits in der Schule machen wir Bekanntschaft mit der klassischen Elektrostatik, Magnetostatik, aber auch der Elektrodynamik. Dabei sind die Maxwell-Gleichungen ein nicht mehr wegzudenkender, wichtiger Teil zur Beschreibung des Zusammenhangs zwischen elektrischen und magnetischen Feldern. Doch was ist, wenn wir weiter gehen, wenn wir den klassischen Pfad verlassen und uns der quantenmechanischen Theorie zuwenden? Finden wir dort unsere Wechselwirkung zwischen Licht und Materie wieder? Gibt es, ähnlich wie die Maxwell-Gleichungen, auch solch prägende Gleichungen?Diese Fragen beschäftigen uns in der vorliegenden Arbeit, wobei dazu zunächst die Korrespondenz der relativistischen Mechanik und relativistischen Quantenmechanik untersucht wird. Weiterführend folgt die Quantisierung von Feldern und diese geht in die Quantenelektrodynamik über. Hier werden, aufgrund des einführenden Charakters, nur Prozesse niedrigster Ordnung betrachtet und ein besonderes Augenmerk liegt auf der Compton-Streuung.

This second edition of Dynamics, Information and Complexity in Quantum Systems widens its scope by focussing more on the dynamics of quantum correlations and information in microscopic and mesoscopic systems, and their use for metrological and machine learning purposes. The book is divided into three parts:Part One: Classical Dynamical SystemsAddresses classical dynamical systems, classical dynamical entropy, and classical algorithmic complexity.Includes a survey of the theory of simple perceptrons and their storage capacity.Part Two: Quantum Dynamical SystemsFocuses on the dynamics of entanglement under dissipative dynamics and its metrological use in finite level quantum systems.Discusses the quantum fluctuation approach to large-scale mesoscopic systems and their emergent dynamics in quantum systems with infinitely many degrees of freedom.Introduces a model ofquantum perceptron whose storage capacity is computed and compared with the classical one.Part Three: Quantum Dynamical Entropies and ComplexitiesDevoted to quantum dynamical entropies and algorithmic complexities.This book is meant for advanced students, young and senior researchers working in the fields of quantum statistical mechanics, quantum information, and quantum dynamical systems. It is self-contained, and the only prerequisites needed are a standard knowledge of statistical mechanics, quantum mechanics, and linear operators on Hilbert spaces.

In this book, Mark P. Fusco offers a historical, philosophical and theological review and appraisal of current research into quantum, post-modern, atheistic, mathematical, and philosophical theories that engage our interpretation of Hans Urs von Balthasar and Ferdinand Ulrich¿s accounts of Ur-Kenosis. This cross-disciplinary approach inspires a new speculative metaphysical theory based on the representation of being as a holo-somatic ontology. Holocryptic metaphysics gives us a novel interpretation of transubstantiation as it is founded on the findings of quantum mechanical theory. The quantum object and black hole¿s properties present a new way to explain physical matter based on its holographic identity. This scientific theory for representing physical matter¿s identity is recognized, for example, in the symmetry existing between a subatomic particle and its orbital shell, a single particle¿s identity in relationship to its thermodynamic system, Hawking radiation, and black hole entropy. Further, the properties of quantum non-locality and teleportation signpost a new way to understand the Eternal Logos¿ relationship to Jesus Christ and the Eucharist.

This helpful and pedagogical book offers problems and solutions in quantum mechanics from areas of current research, rarely addressed in introductory courses or textbooks. It is based on the authors' own experience of teaching undergraduate and graduate courses in quantum mechanics, and adapts problems from contemporary research publications to be accessible to students. Each section introduces key quantum mechanical concepts, which are followed by exercises that grow progressively more challenging throughout the chapter. The step-by-step solutions provide detailed mathematical derivations, and explore their application to wider research topics. This is an indispensable resource for undergraduate and graduate students alike, expanding the range of topics usually covered in the classroom, as well as for instructors and early-career researchers in quantum mechanics, quantum computation and communication, and quantum information.