Introduction

Quantum computing is a lot like the sulfur-spewing hydrothermal vents at the bottom of the Mariana Trench: It’s both hot and deep. (The vents in the Mariana Trench are also surrounded by strange life forms, which implies something not very nice about us, your authors.)

Quantum computing is hot because progress, activity, interest, and investment are all continuing to grow to unprecedented levels. And it’s hot also because popular culture says so. Movies like the 2023 Oscar winner, Everything Everywhere All at Once, and the Netflix series 3 Body Problem make quantum mechanics — the technology that underlies quantum computing — lively, interesting, and even funny.

And why is quantum computing deep? Because it directly applies quantum mechanics to some of the biggest problems that humanity faces today, such as drug discovery, lifespan enhancement, and climate change. And the workings of the quantum world challenge our understanding, sometimes even our grasp on, reality.

Entanglement is a core principle of quantum computing, and the 2022 Nobel Prize in Physics was awarded for work on entanglement. Yet no less a figure than Albert Einstein called entanglement “spooky action at a distance.” Quantum computing depends on this “spooky action” and other quantum mechanical principles to deliver incredible results.

All this makes the two of us very happy to bring you Quantum Computing For Dummies. We hope this book will direct your attention toward the big picture where needed — and also show you when it’s time to, as the expression says, “shut up and calculate.” Or program. Or make hard-nosed business decisions about where to put your time, energy, and money.

About This Book

Quantum Computing For Dummies provides a clear and concise introduction to the terminology, technology, and techniques you need to use quantum computing to get a job, make business decisions, invest, or just introduce yourself to this fascinating new technology.

With this book as your guide, you’ll learn about

• The core principles of quantum mechanics
• How quantum mechanics relates to quantum computing
• Where the technology is today and how it relates to your business and career
• How quantum-inspired computing, a transitional technology, is being used to solve advanced problems on today’s computers
• The difference between quantum annealing, another transitional technology, and gate-based quantum computing — the most complete expression of quantum computing technology
• Which gate-based quantum computing modality to use, based on nearly a dozen types of qubits
• More than a dozen quantum algorithms that might help to solve problems that your business faces today
• Identifying which kind of speedup quantum computing might offer for the problems that affect your business today
• The steps needed to make your business ready for — or a leader in — quantum computing
• Choosing a cloud provider to help you get started with the technology, often for free
• Online courses on how to program quantum computers
• Signing onto a live portal and starting your own quantum computer programming journey
• Resources, online and offline, to further your knowledge or quantum computing
• University programs to help you take the next step toward a quantum computing career

You’re going to be seeing news stories about progress in quantum computing, and you may find yourself discussing the technology with friends or at work. You may even consider taking your career in this new direction. All of which leads to a simple question: What can you actually do about quantum computing?

This book answers that question. It enables you to relate the computers we all use today — called classical computers — to this strange new beast, quantum computing. It shows you what you can do with quantum computers today, and what you will likely be able to do in the future. And it punctures many myths about quantum computing.

The book then goes on to show you how to get started in quantum computing at work, whether that’s programming a quantum computing or using quantum computing in your business. And it helps you understand the technology trends so you can keep an eye on new opportunities as quantum computing moves forward.

Quantum computing is quite different than the classical computers you’re accustomed to. This book can help you decide when to use each type of computing, now and in the future.

You can learn bits and pieces about quantum computing by reading news stories and poking around online. But with this book, you get a complete picture. You can decide whether you and your business need to get started with quantum computing today — and if so, you can roll up your sleeves and get to work.

Foolish Assumptions

Quantum Computing For Dummies is written for beginners, which means you might not even know for sure what quantum computing is. We don’t assume that you know physics or mathematics beyond what common sense tells you. And we don’t assume that you've programmed a computer (of any kind) before.

However, we do assume that you

• Have used a computer or a smartphone or both
• Have access to the internet so you can do further research on new topics
• Are interested in what quantum computing can do for your career, your business, or the world

Icons Used in This Book

If you’ve read other Dummies books, you know that they use icons in the margin to call attention to particularly important or useful ideas in the text. In this book, we use four of these icons.

The tip icon highlights expert shortcuts or simple ideas that can make life in the quantum computing field easier for you.

You could say that this whole book is technical stuff, but this icon highlights information that’s particularly technical. You can re-read information highlighted with this information if you want to go deep, or skip it if you don’t want to know all the details. It’s entirely up to you!

While we would like to think that every word in this book is unforgettable, we’d like you to carry some information to other areas of the book. We highlight these points so you can quickly find important takeaways that matter quite a bit in helping you get up to speed with quantum computing.

Just as you would do if you were driving a car, slow down when you see a warning sign. It highlights an area where it’s easy to make a mistake or develop a misunderstanding.

Beyond the Book

To get to the web page for this book, go to www.dummies.com and type Quantum Computing For Dummies in the Search box. The web page includes the book's cheat sheet, which defines basic terms, describes the different types of quantum computers, lists the most-used types of qubits, and links to some of the online classes about quantum computing. You’ll also find bonus chapters with tech and business information.

Occasionally, the publishers provide updates to Dummies books. If this book has technical updates, you can find them here as well.

To see the free programming introduction mentioned in Chapter 12, go to www.dummies.com/go/quantumcomputingfd.

One of the book’s authors, William Hurley (known as whurley), maintains a personal website with information about quantum computing and other topics of interest. You can visit it at www.whurley.com. whurley is also CEO of Strangeworks, a quantum computing company. You can visit Strangeworks at www.strangeworks.com.

Where to Go from Here

Part 1 introduces you to quantum computing and the most closely related technologies, quantum mechanics and classical computing (the computers you use today). Part 2 is a deep dive into the different ways you can do quantum computing today and the different qubit types used in gate-based quantum computing, the most advanced (and, so far, least developed) form of the technology. Part 3 is quite practical, if we can use that word to describe an almost mystical technology; it introduces you to quantum computing algorithms, quantum computer programming, and educational resources for learning more. And Part 4 is the famous Dummies “Part of Tens”; it gives you lists of key points mentioned in the book, covering both technical and business information.

You can read this book in any way you’d like. If you go straight from beginning to end, the book will take you on a journey from the basics of quantum computing and classical computing to in-depth knowledge of technical topics such as qubits and quantum computing algorithms. It will then show you how to access and program quantum computers and give you a variety of ways to move yourself, your career, and your organization forward with the technology.

At the same time, we understand that you might want to pop in and out of the book. You may want to go deep on topics that interest you and skim other sections. You can look at the topics that interest you in the order that we have them arranged in the book; in your own order, based on your own interests; or in no specific order at all. The book is full of cross-references and signposts...