The purpose of this book is to teach quantum computing hardware from an engineer's perspective. Engineers play an important role in quantum computers. However, college and graduate engineering students usually do not have the required physics and mathematics training to understand how quantum computer hardware works. This book provides step-by-step guidance to connect engineers to the quantum world. Prepares readers with the essential mathematics and physics skills to understand and design quantum computers. Covers spin qubits and superconducting qubits in a unified framework. Uses language accessible to readers with varying backgrounds and a step-by-step approach. Includes simulation codes and superconducting quantum chip design examples. Discusses step-by-step the physics, mathematics, and their connection to microwave electronics based on how they fulfill the five DiVincenzo's criteria.