Preface

The theory of quantum computing and communication has made remarkable progress over the years and has become a significant scientific discipline. It encompasses many concepts related to quantum information technologies, including quantum algorithms, quantum computers, quantum code, post-quantum cryptography, quantum key distribution, and quantum teleportation.

This book surveys the field of quantum computation and quantum communication from a fresh perspective, discussing its representative technologies and the latest research. The introductory chapter provides an overview of the topic and the book. Chapter 2, "Quantum Algorithms for Nonlinear Equations in Fluid Mechanics", gives a narrative tutorial on quantum algorithms. Chapter 3, "A Novel Three-Input XOR Gate Based on Quantum Dot-Cellular Automata with Power Dissipation Analysis", presents the "quantum code" notation and restates many of the examples and results of the preceding chapter. Chapter 4, "Topology in Photonic Discrete-Time Quantum Walks: A Comprehensive Review", provides a comprehensive review of photonic implementations of discrete-time quantum walks in the spatial and temporal domains. Chapter 5, "Introduction to Quantum Computing", explains how a quantum computer might be built. Chapter 6, "Multipoint-Interconnected Quantum Communication Networks", discusses some quantum applications, including quantum key distribution and teleportation along with related development and research.

We would like to thank Dr. Rene Steijl, Professor Ismail Gassoumi, Professor Graciana Puentes, and Professor Surya Teja Marella for their help in writing some chapters. We also received help, support, and encouragement from many other individuals and institutes. We would also like to thank those physicists and computer scientists who have developed the field of quantum computation and quantum communication.

> **Yongli Zhao** Beijing University of Posts and Telecommunications, Beijing, China
