The quantum computing market is predicted to grow by nearly $1.3 billion over the next five years. Why? Given their quantum mechanical nature, quantum computers are expected to solve difficult problems in chemistry, optimization, finance, and machine learning that classical computers find impossible to unravel.

This pocket guide provides software developers with a quick reference to Qiskit, an open source SDK for working with quantum computers. Packed with helpful programming examples, tables, figures, and lists, this handy book helps you find the information you need to develop and debug quantum programs.

Whether you're focused on business, engineering, or scientific applications, you'll learn how to choose and apply appropriate Qiskit classes, methods, and functions.

• Learn how to create quantum circuits, define quantum gates, and leverage the transpiler
• Explore modules for implementing quantum information concepts and quantum algorithms
• Survey features of Qiskit that abstract and facilitate working with various quantum computers and simulators
• Learn how to use the latest version of the Open Quantum Assembly Language

Qiskit is an open source SDK (software development kit) for working with quantum computers at the level of pulses, circuits, and application modules. The purpose of this book is to provide a succinct guide for developers to use while creating applications that leverage quantum computers and simulators.

We hope this book will enable developers to actively participate in the open source Qiskit community. The Qiskit community, as well as documentation, tutorials, and other resources, is available at Qiskit.

Table of Contents

Part I. Qiskit Fundamentals

Chapter 1. Quantum Circuits and Operations

Chapter 2. Running Quantum Circuits

Chapter 3. Visualizing Quantum Measurements and States

Chapter 4. Using the Transpiler

Part II. Quantum Information and Algorithms

Chapter 5. Quantum Information

Chapter 6. Operator Flow

Chapter 7. Quantum Algorithms

Part Ill. Additional Essential Funct ionality

Chapter 8. Qiskit Circuit Library Standard Operations

Chapter 9. Working with Providers and Backends

Chapter 10. OpenQASM

How This Book Is Structured

Our goal in this guide is to address much of the functionality of Qiskit that application developers will routinely use. Some of this Qiskit functionality is considered to be fundamental to quantum computing. Other Qiskit functionality supports quantum computing concepts such as quantum information and quantum algorithms. Qiskit has additional functionality that we’ve deemed essential for quantum application development. We’ve structured the book at a high level according to the aforementioned functionality, with individual chapters drilling into the specifics. The chapters are divided into three parts:

Part I, Qiskit Fundamentals: In the first part of the book, we show you how to use Qiskit to create quantum circuits. Quantum circuits contain instructions and gates, so we discuss how to use the ones provided in Qiskit, as well as how to create your own. We then show you how to run quantum circuits on quantum computers and simulators and demonstrate how to visualize results. To round out Part I, we discuss the transpiler and how it converts a quantum circuit into instructions that run on a target quantum computer or simulator.

Part II, Quantum Information and Algorithms: In the second part of this book, we discuss Qiskit modules responsible for implementing quantum information concepts (specifically states, operators, channels, and measures). We also present facilities in Qiskit that implement quantum algorithms, as well as a facility known in Qiskit as operator flow. A developer may use some of the functionality in Part II to develop quantum applications at higher levels of abstraction than quantum circuits.

Part III, Additional Essential Functionality: In the third and final part of this book, we cover essential Qiskit functionality, some of which drills into information already discussed and some of which is newly presented. Specifically, we explore the standard operations of the Qiskit circuit library, and new ground is uncovered when we discuss how to work with quantum providers and backends. In addition, we’ll introduce QASM 3.0 and demonstrate how to create quantum programs with this quantum assembly language.

Review

"Qiskit Pocket Guide is a convenient, compact Qiskit reference book for quantum programming all in one place."  -Jay Gambetta, IBM Fellow and VP of IBM Quantum

"This pocket guide is an excellent overview of core Qiskit functionality with a concise, yet practical, code-first approach. "-Abby Mitchell, Quantum Developer Advocate

"Learning quantum computing can be daunting, and remembering all the functionality in the Qiskit API can be equally so. This book provides a necessary companion for coders who want to take full advantage of the power and elegant features provided by Qiskit."-Dr. Bob Sutor. Quantum industry expert and author, Dancing with Qubits and Dancing with Python

"This is an incredibly handy book - for beginners and advanced users alike - that describes the many functionalities and features of Qiskit, organized in a clear and intuitive way. I expect it is unlikely to find its way off my desk and into a bookshelf any time soon."-Dr. John Watrous, Technical Director, IBM Quantum Education

"Concise yet extensive, this belongs in the pocket of every Qiskit developer." -Lia Yeh, CS PhD student, Quantum Group, University of Oxford

"Very crisp and clear book for quantum developers of all levels!" -Robert Loredo, IBM Quantum Ambassador Worldwide Lead

"A clear and well-organized reference; readers exploring quantum programming will enjoy simple and specific steps to get QPU programs up and running, while even experienced Qiskit users may discover some surprising features." - Eric R. Johnston, co-author of Programming Quantum Computers by O'Reilly Media

About the Author

James L. Weaver is a developer, author, and speaker with a passion for quantum computing. He is a Java Champion, and a JavaOne Rockstar. James has written books including Inside Java, Beginning J2EE, the Pro JavaFX series, and Java with Raspberry Pi. As an IBM Quantum Developer Advocate, James speaks internationally about quantum computing with Qiskit at quantum and classical computing conferences.

Frank J. Harkins is a developer and writer from the north of England. He graduated with a physics degree from the University of Leeds in 2018 and currently works for the Qiskit community team, creating tools for anyone teaching or learning about quantum computing. Frank plays the guitar and enjoys the outdoors.