This book presents a comprehensive treatment of quantum theory using theoretical variables as its foundation. The work progresses from fundamental quantum mechanical principles to sophisticated applications in quantum field theory and gravity. It provides rigorous mathematical frameworks while establishing connections between theoretical physics and practical engineering applications and includes:Presents an advanced treatment of quantum theory across two interconnected partsExamines Bell experiments, quantum probability, information theory, and connections to relativityExtends these foundations to explore quantum field theory, gravity, and noise theoryBridges the gap between theoretical physics and engineering applicationsCovers topics from Yang-Mills fields, quantum gravity to neural networks and biomedical applications of quantum electrodynamicsAddresses quantum measurement of gravitons, Hawking radiation, classical and quantum neural networks with practical examplesProvides mathematical frameworks for understanding quantum phenomena in applied contextsParticularly suitable for graduate students and researchers in physics, mathematics, and engineering disciplines seeking to understand quantum phenomena across theoretical and applied domains. This title has been co-published with Manakin Press. Taylor & Francis does not sell or distribute the print edition in India, Pakistan, Nepal, Bhutan, Sri Lanka and Bangladesh.