Quantum Computing for Everyone (Mit Press)

Despite being around for decades, the words “quantum mechanics” still make eyes roll even in a room of educated people. Few really understand the phenomena. Among those more scientifically minded, some – thankfully fewer in number – still argue that quantum mechanics will give way someday to a more classical approach. The controversial part of quantum mechanics, which foiled even Albert Einstein, states that to measure the spin or velocity of an electron, one must interfere with the system permanently. This enmeshment of the measurer with the system confuses people, but numerous experiments highlight this paradox. It seems to be an innate part of the universe, not merely a technological limitation.Smart physicists and mathematicians have noticed an opportunity around quantum mechanics: We can address computational questions with its approach. A system of “qubits” can be used to address problems that classical computing cannot address. This observation has produced a new scientific field of quantum computing. Recently, major companies have begun to jump into this technology in a quest for early supremacy.Most textbooks use a lot of math to introduce quantum computing – rightfully so because mathematics provide the basis towards all computation. But a math-heavy approach makes the field relatively inaccessible. To address this shortcoming, Chris Bernhardt provides an introduction to the subject with less mathematics. The book teaches basic linear algebra needed to approach the subject. It’s still heavy on the words, not the mathematics, and draws out applications and challenges that confront the field.Since a child, I have loved mathematics and its creative expressivity. I enjoyed how Bernhardt introduced me to relevant concepts and drew me into quantum concepts. By the end of the book, however, I glazed over the mathematics in favor of just getting the book completed. Perhaps that is a personal failing, but it’s one that I witnessed in many of my college math classes, too!I found the next-to-last chapter on quantum algorithms the least accessible, but the last chapter on quantum applications was the most interesting. Those in the investment community can find a deep dive into this topic helpful to carefully discover future winners and losers in this burgeoning field. Quantum computing presently requires a lot of money to access, but presumably, like classical computing, that cost will go down with time. This field is fascinating to think about, and Bernhardt makes it truly accessible “for (almost) everyone.”

This book will not turn you into an expert on quantum computing, but it is impossible to imagine a clearer yet thorough introduction to the underlying concepts. The book uses linear algebra to discuss quantum physics —no surprise there— but instead of dragging the student through full blown infinite dimensional Hilbert Spaces, Dr. Bernhardt uses only a two- dimensional (mostly) vector space over Real numbers to illustrate the concepts. The explanations of each new bit of information are amazing clear, so the book really requires only a background of high school math. However, the simplified approach does not mean the subject is hopelessly watered down. The reader ends up understanding things like tensor products of kets and the Kronecker tensor product of matrices. All in all, Dr. Bernhardt does a superb job.There are a few minor typos and there is an errata available at http://faculty.fairfield.edu/cbernhardt/Errata%20to%20Quantum%20Computing%20for%20Everyone.pdf.This book gives you a solid introduction, but follow on texts will be necessary if you hope to actually create quantum programs and design algorithms. So will a lot more math.All in all, I found this book to be truly excellent introduction to a subject that can be daunting. You will need to stop, think, and re-read at times to get the most out of it, but it clear, accessible and well written. I recommend it.

Quanting computing for everyone provides a readable introduction to the mathematical structure of computing with qubits. The author does a fine job of introducing a challenging subject to the reader, and by using only real coefficients for quantum states, does a novel job of smoothing over the complexities of phase. The level is around the same as the author's other work "Turing's Vision", and is approachable but has its challenges and there are certain parts where the uninitiated will have to gloss over and perhaps return or just try to absorb the big picture concept.The book is split into 9 chapters and the first 6 are the most readable. The first chapter where the author describes spin includes a practical experiment anyone can do with polarized filters that displays the remarkable consequences of quantum mechanics and measurement. The author then gets into linear algebra and its use in formalizing the structure of quantum mechanics. I think the author does a great job of guiding the reader through a deep subject with concrete examples of how was switches basis, what it means and row and column space. The author then goes back to quantum mechanics and discusses qubits and how spin 1/2 particles can encode qubits. The author gets into privacy experiments with the infamous Alice, Bob and Eve to illustrate how encryption scenarios are described. The author then tackles the profound issues of entanglement and measurement. In particular the author introduces the reader to tensor product spaces and the construction of entangled states that cannot be a combination of individual particle basis states. The author is able to introduce Bell's inequality and non-locality which is a feat in itself as it is a remarkable result and the author does it with just using real coefficients for a 3 particle system. The author then moves on to basic circuit logic and the construction of universal gates. Boolean logic is of course discussed as well as how one can build functions from logic gates. The author introduces concepts like reversible computation and brings up that one can compute with analog machines set up in appropriate initial conditions and the concept of computation flows far outside of traditional computer science and into the realm of physics. The material starts to get challenging when he starts to describe quantum gates and computation. Though the material is self contained it is not the easiest to follow as ideas start to build through layers of logic. Finally the author gets into how one can use quantum algorithms to solve NP problems for efficiently than is currently possible through classical algorithms. He discusses the wave of innovation in ideas in quantum computing in the 80s and introduces Shor's algorithm but at a high level given how involved some of the properties are.Overall Quantum Computing for Everyone is readable but challenging. I think a variety of readers can get something out of the book. I think it unlikely that one has the ability to use this book to become well acquainted with the subject but it can be used to get a sense of the ideas and it can be used by those well versed to get some intuitive communication about ideas they already know. Definitely worth trying to go through for those interested in the subject and could be read as supplemental to a text book for those looking for both substance and intuition.

Extremely informative. In depth information. Throwaway covers subject.