Quantum Computing: An Applied Approach by Jack Hidary

BOOK REVIEW | By: Nathan Schor | Oct 17, 2020

The book does an excellent job of fully covering a challenging subject

in a digestible way while maintaining the reader’s appetite.

I wrote a comprehensive positive review of the 1st Edition which many prospective readers found helpful and since the 2nd Edition adds even more reasons why the book deserves attention, it makes sense to upgrade the original review with a summary of the enhancements in the 2nd Edition.

As described in the original review – included below – the book contains multiple paths into learning QC, reflecting the varied backgrounds of those entering the industry. However, the book’s most beneficial overall feature is its recency, a significant attribute in the highly dynamic QC industry with breakthroughs on multiple fronts occurring with increasing frequency, especially in the three years since the 1st Edition.

And with regard to staying on top of emerging societal impacting technology, the author, Jack Hidary, appears to be an experienced guide. Although not mentioned in book, but worth noting here, his most recent initiative, SandboxAQ, is a firm dedicated to merging AI with QC.


There’s expanded coverage of recent developments in Quantum Machine Learning and Quantum Hardware, along with more material detailing the important area of Quantum Error Correction. The chapter on Quantum Mechanics now includes a solid section on the Schrodinger Equation.

Also noteworthy are these two new sections. One on the QSVT Framework, an important recent advance in classifying algorithms. And the second, on Dirac Notation which beginners will find useful as fluency in it is essential to learning QC.


Reading ‘Quantum Computing – An Applied Approach’ by Jack Hidary was time and money well spent since it’s actually three books in one. As such, it is neatly organized in three major sections – (1) Foundations (2) Hardware and Applications (3) Toolkit, broadly reflecting the three disciplines intersecting to construct Quantum Computing (QC) – physics, computer science and math.

Because of that triplet packaging the book accommodates a wide band of readers. The highly useful Navigating chapter lists five classes – University Instructors, Physicists, Software Programmers, Business Leaders, Independent Study – and recommends for each of those categories the optimal learning path across the extensive content.

So you may not want to read the book in the specific order it’s printed, and instead make your own way through content depending on your specific interests and background. However, everyone should read the first two chapters which nicely summarize the history of quantum computing, along with describing a device with the astonishing properties which are not possible in a classical machine. After that, it’s design your journey or simply follow the books order.

For example, I’m in the Independent Study group, so found starting with the math the best move. Since QC is spoken in Linear Algebra, not understanding its basic principles means QC will soon become incomprehensible. Fortunately, Linear Algebra is relatively the easiest math to learn (compared to Analysis/Calculus) and the book does excellent job of aggregating the essentials you’ll need to know to become conversant in QC. The math section covers all the machinery needed to fluently participate in quantum computing and is both rigorous and readable.

At any rate, there’s a five minute self-test at beginning of the math section which will help you in deciding how much attention to spend in that section. If you’re in the Business Leader category, then you’ll want to begin here.


True to its name, the book’s focus is distinctly on applications. This is where it surpasses the many other books on QC because it has distinct advantage of being up to date, all the more useful in a dynamic field like QC.

Many books on QC were written prior to the significant advances over the last decade, and especially in the last three years, leading to several promising results in applying QC in commercial sectors from finance to pharmaceuticals. Indeed, it is precisely such progress which makes it possible to write a solid book with ‘applied’ in its title. And to maintain its freshness factor there’s a GitHub site populated with learning resources and technical updates.

Having the latest info is vital in a dynamic area like QC. With improvements occurring regularly.. there’s an advantage of a timely publication. For example, in October 2019 Google claimed its quantum computer demonstrated quantum supremacy, a long sought goal in the industry. Since the author works at Alphabet X, it’s not surprising there’s a chapter devoted to quantum supremacy, explaining what it takes to prove such a claim as opposed to merely asserting ‘quantum advantage’. Also described are several application areas where there’s active research in such programs.


Outside its obvious usefulness in a classroom, there are three discernable groups of readers who’d find this book worthwhile. First and foremost those with coding experience looking to become involved with QC. Next are those with a STEM background. Third, readers (like me) without STEM accreditation, perhaps with business degrees, but with an understanding of modern science.

For sure, if you’re in the latter group, then this neatly organized book will bring you up to speed on this steadily emerging technology. Even if you don’t fully absorb the more technical sections, there’s plenty of clear material to make you both conversant in the subject and able to assess opportunities as the sector starts to enter the commercial mainstream.

It’s also a useful first book for those with some STEM training who’re looking to come up to speed on quantum computing. They’ll benefit from the extensive coverage applications receive, way beyond what’s contained in other QC texts.

The book is especially worthwhile for those with some technical exposure to this area like  programmers – as there’s plenty of places to dive into code and interact on GitHub.


If you’re motivated to learn then ‘Quantum Computing – An Applied Approach 2nd Edition’ deserves your consideration. Especially if you have some STEM training or even if you enjoy learning fascinating math/physics.

For the serious reader, the book serves as an informative first text on QC.

In addition, it also makes a decent handbook. As you learn more QC and become more adapt, it’s a good book to return to, serving as a reference and refresher for core material.

Overall, the book does an excellent job of fully covering a challenging subject in a digestible way while maintaining the reader’s appetite. Depending on your STEM credentials, there may be some challenging topics, but in fairness, that is not unexpected for taking on such a difficult and demanding subject.

There’s sufficient material so no matter what the reader’s level, it will elevate your quantum computing knowledge.  Enjoy the journey.