This book is the second volume in the series New Era Electronics, a compilation of lecture notes defining the important concepts tied to the electronics transition happening in the 21st century. Quantum communication is introduced in this volume through the coverage of relevant, basic concepts of quantum mechanics and the introduction of quantum elements of a quantum optical communication system. Also included is a quantum description of electromagnetic fields and its interaction with atoms to generate, store, measure and control quantum optical information encoded onto optical fields. By taking a conceptual and less mathematical approach to quantum optics and quantum information, this book becomes accessible to broader audiences and engineers working actively in the technical field. The reader is only required to have a basic understanding of undergraduate linear algebra. These notes introduce the basic quantum processes and devices used in quantum communication applications. The boundary between classical and quantum physics, the quantization of electro-magnetic field and its consequences, quantum electromagnetic and atomic physics, and their applications in quantum communication are discussed. The device and experimental aspects of quantum key distribution, quantum teleportation, quantum memories, entanglement distribution, and quantum repeaters are also discussed.