Exploring Quantum Contextuality With Photons

This thesis uses high-precision single-photon experiments to shed new light on the role of reality, causality, and uncertainty in quantum mechanics. It provides a comprehensive introduction to the current understanding of quantum foundations and details three influential experiments that significantly advance our understanding of three core aspects of this problem. The first experiment demonstrates that the quantum wavefunction is part of objective reality, if there is any such reality in our world. The second experiment shows that quantum correlations cannot be explained in terms of cause and effect, even when considering superluminal influences between measurement outcomes. The final experiment in this thesis demonstrates a novel uncertainty relation for joint quantum measurements, where the textbook relation does not apply.

This book explores two of the most striking features of quantum theory – contextuality and nonlocality – using a formulation based on graph theory. Quantum theory provides a set of rules to predict probabilities of different outcomes in different experimental settings, and both contextuality and nonlocality play a fundamental role in interpreting the outcomes. In this work, the authors highlight how the graph approach can lead to a better understanding of this theory and its applications. After presenting basic definitions and explaining the non-contextuality hypothesis, the book describes contextuality scenarios using compatibility hypergraphs. It then introduces the exclusivity graph approach, which relates a number of important graph-theoretical concepts to contextuality. It also presents open problems such as the so-called Exclusivity Principle, as well as a selection of important topics, like sheaf-theoretical approach, hypergraph approach, and alternative proofs of contextuality.

The counter-intuitive aspects of quantum physics have been long illustrated by thought experiments, from Einstein's photon box to Schrödinger's cat. These experiments have now become real, with single particles - electrons, atoms, or photons - directly unveiling the strange features of the quantum. State superpositions, entanglement and complementarity define a novel quantum logic which can be harnessed for information processing, raising great hopes for applications. This book describes a class of such thought experiments made real. Juggling with atoms and photons confined in cavities, ions or cold atoms in traps, is here an incentive to shed a new light on the basic concepts of quantum physics. Measurement processes and decoherence at the quantum-classical boundary are highlighted. This volume, which combines theory and experiments, will be of interest to students in quantum physics, teachers seeking illustrations for their lectures and new problem sets, researchers in quantum optics and quantum information.

This book focuses on the gradual formation of the concept of ‘light quanta’ or ‘photons’, as they have usually been called in English since 1926. The great number of synonyms that have been used by physicists to denote this concept indicates that there are many different mental models of what ‘light quanta’ are: simply finite, ‘quantized packages of energy’ or ‘bullets of light’? ‘Atoms of light’ or ‘molecules of light’? ‘Light corpuscles’ or ‘quantized waves’? Singularities of the field or spatially extended structures able to interfere? ‘Photons’ in G.N. Lewis’s sense, or as defined by QED, i.e. virtual exchange particles transmitting the electromagnetic force? The term ‘light quantum’ made its first appearance in Albert Einstein’s 1905 paper on a “heuristic point of view” to cope with the photoelectric effect and other forms of interaction of light and matter, but the mental model associated with it has a rich history both before and after 1905. Some of its semantic layers go as far back as Newton and Kepler, some are only fully expressed several decades later, while others initially increased in importance then diminished and finally vanished. In conjunction with these various terms, several mental models of light quanta were developed—six of them are explored more closely in this book. It discusses two historiographic approaches to the problem of concept formation: (a) the author’s own model of conceptual development as a series of semantic accretions and (b) Mark Turner’s model of ‘conceptual blending’. Both of these models are shown to be useful and should be explored further. This is the first historiographically sophisticated history of the fully fledged concept and all of its twelve semantic layers. It systematically combines the history of science with the history of terms and a philosophically inspired history of ideas in conjunction with insights from cognitive science.

The book explores the variety of meanings of contextuality across different disciplines, with the emphasis on quantum physics and on psychology. Contents:Conversations on Contextuality (Ehtibar N Dzhafarov & Janne V Kujala)Contextual Semantics (Samson Abransky)From Coupling to Copula (Hans Colonius)Einstein, Bohm, and Leggett-Garg (Guido Bacciagaluppi)It is the Theory Which Decides What We Can Observe (Thomas Filk)Reality, Contextuality, and Probability in Quantum Theory and Beyond (Arkady Plotnitsky)Contextual Emergence (Harald Atmanspacher)Contextuality in Physics and Quantum Cognition (J Acacio de Barros & Gary Oas)End-Directedness and Context in Nonliving Dissipative Systems (James A Dixon, Dilip Kondepudi, Bruce A Kay & Tehran J Davis)Foregrounding the Background (J Scott Jordan, Jiuyang Bai, Vincent Cialdella & Daniel Schloesser)Symmetry-Breaking in Multiagent Coordination (Michael J Richardson & Rachel W Kallen)Probabilistic Contextuality (Janne V Kujala & Ehtibar N Dzhafarov)Quantum Thinking and Counterfactual Reasoning (Louis Narens)Quantum Theory, Active Information and the Mind-Matter Problem (Paavo Pylkkänen)Principles Defining Quantum Mechanics (Gary Oas & J Acacio de Barros)Our (Represented) World: A Quantum-Like Object (Ariane Lambert-Mogiliansky & Francois Dubois)Why Would You Want to Borrow from My Discipline? (Emmanuel Haven)Quantum Information Biology (Masanari Asano, Irina Basieva, Andrei Khrennikov, Masanori Ohya, Yoshiharu Tanaka & Ichiro Yamato)Similarity Judgments: From Classical to Complex Vector Psychological Spaces (Albert Barque Duran, Emmanuel M Pothos, James M Yearsley, James A Hampton, Jerome R Busemeyer & Jennifer S Trueblood)A Quantum Bayes Net Approach to Causal Reasoning (Jennifer S Trueblood, Percy K Mistry & Emmanuel M Pothos) Readership: Researchers in quantum physics, mathematical modelling and cognitive science. Key Features:It is historically the first book dedicated entirely to contextualityIt is interdisciplinary, involving quantum physicists, computer scientists, mathematicians, analytic philosophers, economists, and psychologistsIts chapters are written by leading specialists in these various fieldsKeywords:Contextuality;Quantum Physics;Psychology

Forget everything you thought you knew about reality. The world is a seriously bizarre place. Things can exist in two places at once and travel backwards and forwards in time. Waves and particles are one and the same, and objects change their behaviour according to whether they are being watched. This is not some alternative universe but the realm of the very small, where quantum mechanics rules. In this weird world of atoms and their constituents, our common sense understanding of reality breaks down - yet quantum mechanics has never failed an experimental test. What does it all mean? For all its weirdness, quantum mechanics has given us many practical technologies including lasers and the transistors that underlie computers and all digital technology. In the future, it promises computers more powerful than any built before, the ability to communicate with absolute privacy, and even quantum teleportation. The Quantum World explores the past, present and future of quantum science, its applications and mind-bending implications. Discover how ideas from quantum mechanics are percolating out into the vast scale of the cosmos - perhaps, in the future, to reveal a new understanding of the big bang and the nature of space and time. ABOUT THE SERIES New Scientist Instant Expert books are definitive and accessible entry points to the most important subjects in science; subjects that challenge, attract debate, invite controversy and engage the most enquiring minds. Designed for curious readers who want to know how things work and why, the Instant Expert series explores the topics that really matter and their impact on individuals, society, and the planet, translating the scientific complexities around us into language that's open to everyone, and putting new ideas and discoveries into perspective and context.

Quantum computers are the proposed centerpieces of a revolutionary, 21st-century quantum information technology. This book takes the reader into the world of quantum mechanics and continues on an in-depth study of quantum information and quantum computing, including the future of quantum technology. This text focuses on what is "quantum" about quantum mechanics; topics discussed include the EPR paradox, entanglement, teleportation, Bell's Theorem, quantum computing, and code-breaking with quantum computers.--Back cover.