I 全局概览

I Fundamental concepts
1 Introduction and overview
Science offers the boldest metaphysics of the age. It is a thoroughly human
construct, driven by the faith that if we dream, press to discover, explain, and
dream again, thereby plunging repeatedly into new terrain, the world will somehow come clearer and we will grasp the true strangeness of the universe. And
the strangeness will all prove to be connected, and make sense.
– Edward O. Wilson
Information is physical.
– Rolf Landauer
What are the fundamental concepts of quantum computation and quantum information?
How did these concepts develop? To what uses may they be put? How will they be presented in this book? The purpose of this introductory chapter is to answer these questions
by developing in broad brushstrokes a picture of the field of quantum computation and
quantum information. The intent is to communicate a basic understanding of the central
concepts of the field, perspective on how they have been developed, and to help you
decide how to approach the rest of the book.
Our story begins in Section 1.1 with an account of the historical context in which
quantum computation and quantum information has developed. Each remaining section
in the chapter gives a brief introduction to one or more fundamental concepts from the
field: quantum bits (Section 1.2), quantum computers, quantum gates and quantum circuits (Section 1.3), quantum algorithms (Section 1.4), experimental quantum information
processing (Section 1.5), and quantum information and communication (Section 1.6).
Along the way, illustrative and easily accessible developments such as quantum teleportation and some simple quantum algorithms are given, using the basic mathematics
taught in this chapter. The presentation is self-contained, and designed to be accessible
even without a background in computer science or physics. As we move along, we give
pointers to more in-depth discussions in later chapters, where references and suggestions
for further reading may also be found.
If as you read you’re finding the going rough, skip on to a spot where you feel more
comfortable. At points we haven’t been able to avoid using a little technical lingo which
won’t be completely explained until later in the book. Simply accept it for now, and come
back later when you understand all the terminology in more detail. The emphasis in this
first chapter is on the big picture, with the details to be filled in later.