“Quantum Computing for Everyone” by Chris Bernhardt

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Rating: 4/5 Stars

A fascinating book and a topic that may be easily misunderstood: the application of quantum mechanics to computing. The author does not shy away from the maths of linear algebra and matrix computations, but if you stick with it and work through or think about the maths, you’ll get a better understanding of how quantum computing works, instead of getting a ‘hand-wavy’ non-mathematical view.

The book starts with the basics of quantum mechanics: how the act of measurement alters the properties of a quantum object like light (photons) or electrons. Next, linear algebra and matrix computations are introduced, and it is probably best for the reader to work through or become familiar with this, or much of the rest of the book will be incomprehensible. Next, the mathematics are then used to show how measurements of quantum objects cause them to take on the measured states: this is the ‘shut up and calculate’ form of quantum mechanics, where not much is said about what quantum mechanics is, but only about what it does.

Using mathematics, the author then shows what happens when two particles are entangled and their states measured. He carefully shows how measuring the state of one entangled particle ‘instantaneously’ causes another particle to take another known state, and why this does not lead to ‘faster than light’ communication. He also shows the calculations on how Bell’s Inequality shows that quantum entanglement is real and not a due to a ‘hidden variables’ form involving classical particles.

The author then switches topics to introduce logic gates, which leads to the topic of quantum gates. Again, mathematics is used to show how such quantum gates work. These quantum gates are then combined to produce quantum circuits, which are then used to show how ‘superdense coding’ and quantum teleportation work.

Finally, the work culminates by looking at quantum algorithms and how they achieve ‘better’ results and classical algorithms. Finally, a brief look at how quantum computers could perform better than their classical counterparts is given.

Book read from 2024/06/11 to 2024/06/18