I can't remember why I put this book on my get-at-library list; it was a while ago (pre-pandemic). But there it was; I requested UNH's Dimond Library to get it via Interlibrary Loan, and it showed up from Tufts.
It was not quite what I expected, and I mean that in a good way.
First, it's hilarious. The author, Jonathan P. Dowling, peppers his text with wry observations and jokes. I read a lot of dilettante-level physics books, and I'm pretty sure this is the only one with stories I read aloud to my wife. She even laughed at a few of them. (It helps to have a physics degree under your belt.)
Second, it's opinionated. That's not rare these days, but Dowling turns it up to eleven.
Third, there are many inside-baseball descriptions of how physics is done in the 21st century: funding, employment, refereeing papers, meetings, protecting your turf, bullshitting, confronting charlatans. Dowling is merciless in taking apart the "hippie" view of quantum mechanics. (E. g, Gary Zukav's The Dancing Wu Li Masters, the movie What the Bleep Do We Know!?.)
He's even merciless in discussing non-hippies. On Roger Penrose:
I have read his book and heard him talk on the subject, and as far as I can tell, his argument goes like this. Penrose does not understand how quantum mechanics works, and he does not understand how his brain works, and hypothesizes that quantum mechanics is needed to understand the working of the mind.
Note: Roger Penrose is a Nobel Laureate in Physics. Dowling isn't afraid to punch upward.
Well, enough of that. What's the book about? It starts out by describing the weirdness of QM, specifically the features that bothered Einstein so much. Dowling breaks the weirdness down into three related features: uncertainty (you don't know an experimental result until you measure); unreality (the measure doesn't really exist until you measure); and nonlocality (measuring at point A can affect a measurement of an "entangled" property at point B. And B can be across the room from A, or light years away.) I found the defense of spooky old quantum mechanics to be as good, if not better, than anything else I've read. I felt marginally smarter.
But the meat of the book is quantum computing. Dowling points out there are problems that are effectively non-solvable by classical computers, no matter how fast. He uses the example of the thulium atom, which has 69 quantum-entangled electrons; it manages to "solve" its own wave equation only slightly slower than instantaneously due to that entanglement. How can this power be exploited for human ends?
The discussion gets pretty deep into the weeds; Dowling eschews equations, but breaks out the Bra-Ket notation pretty willy-nilly. You either follow this or you don't; I (sigh) did not.
But the "killer app" is actually a dagger aimed at the heart of the Internet-as-we-know-it. If a sufficiently powerful quantum computer existed, it could run "Shor's Algorithm" to factor very large numbers. And the encryption used to secure internet traffic relies on that being impossible.
The end of the book is very blue-sky. Quantum AI? Sure. Conscious computers? Why not. Doomsday scenarios (Terminator, Colossus, Borg, etc.)? Maybe!
For an active field, the book is kind of dated (2013). But (as near as I can tell) progress on Internet-breaking has been (at best) marginal, and some people have wondered if it's achievable. An article from earlier this month: NSA: We 'don't know when or even if' a quantum computer will ever be able to break today's public-key encryption. (Of course, the NSA might be saying that even as they have a bunch of quantum computers right now in some basement at Fort Meade spying on the Chinese.)
Some sad news, given the above: Dowling died last year. I didn't know that until I googled him in writing up this report. I also learned that he wrote a second book, Schrödinger’s Web: Race to Build the Quantum Internet, so that one is now on my get-at-library list.