Quantum Computing From The Ground Up

"Both this book and the next book I’ve recommended, Quantum Computing for Computer Scientists, mention Quantum Computing and Quantum Information (the fifth book on my list) as the real reference book. Both these books say they are, in some sense, introductions to that book. What I really like about the Riley book, Quantum Computing from the Ground Up, is the description of Bell’s Inequality and what that means. If we go back to the 1920s and 30s, when quantum mechanics was first being described, Einstein really disliked it. He really felt that this idea in quantum physics of things jumping when they are measured, of probabilities coming in, shouldn’t be there. He didn’t like the idea of entanglement, where you have what he described as “spooky action at a distance.” So, he felt it was fundamentally wrong and there was a dialogue going on between Einstein and Bohr about what physics was and whether quantum mechanics was the correct way of describing things. In the 1960s John Stewart Bell came up with a really clever experiment. He realized you could distinguish between the theory that Einstein was describing and the standard, Copenhagen theory that Bohr was in favour of. He devised this test, which has subsequently been performed several times, and it’s always come out in favour of Bohr and the Copenhagen description. “I think quantum computing is going to become part of the standard education, certainly of computer scientists and perhaps of most scientists.” This is a really important test and not just for historical reasons. It’s also because as you begin to learn a little bit about quantum phenomena you feel—or at least I did—much like Einstein, that there must be some sort of deeper theory, that it’s got to be simpler, that it can’t really be this strange. I think most people feel that way when they come across quantum mechanics. This test shows you quantum mechanics really does have these strange properties. And then of course once you’ve got a clever idea you want to use it in other ways. The idea behind Bell’s test is now used in many encryption techniques, to encrypt data. It would have been really interesting to see what he made of it. It’s too short to be a textbook, I think. In a couple of places, it’s very terse. What’s very good about it is that it’s got lots of very clear, worked examples that you can read through. It’s a really good book if you want to learn about quantum computing on your own."