Principles of Quantum Computing

You are on a video call. On the other side of the screen is a colleague who has read the vendor deck, watched the keynote, and now wants to know whether the company should spend a quarter of a million dollars on a quantum computing pilot in the next fiscal year. They are looking at you the way people look at engineers when they need a real answer.What you need is not a keynote. What you need is a working engineer's mental model of what a quantum computer actually is, what it can and cannot do today, and what constraints will still be in place three and five years from now.Principles of Quantum Computing is that mental model, written down.This is the second book in The Quantum Engineer Series-a three-book progression for practicing engineers. Book 1 orients you. Book 2 (this volume) grounds you in the physical and computational principles behind every device you will touch. Book 3 shows you how the field turns fragile qubits into reliable ones through error correction.Written in plain English and organized around engineering scenarios, chapters cover: the engineer's mental model for qubits and superposition, entanglement and the Bloch sphere, decoherence and gate error, algorithmic advantage and its limits, hybrid classical-quantum workflows, hardware modalities (superconducting, trapped ion, neutral atom, photonic), benchmarking and vendor evaluation, staffing and organizational readiness, and the honest state of what quantum computing can and cannot deliver today.This book is for the working engineer who has to make real decisions about quantum computing pilots, quantum vendors, quantum roadmaps, and quantum talent-without the equation-heavy overhead of a physics textbook or the marketing gloss of a vendor deck.Book 2 of 3 in The Quantum Engineer Series.