Skip to main content

Computing with Quantum Cats – John Gribbin ****

A new John Gribbin book is always a delight, and he is at his best when exploring the bizarre possibilities of quantum theory. If you aren’t familiar with his previous books on the subject, the title here might be worrying as it suggests some fiendish bio-electronic device where collections of unwilling cats are wired into a computer, but in fact it’s a follow on from earlier titles In Search of Schrödinger’s Cat and Schrödinger’s Kittens, where the relevance of the cats to the topic has become increasingly strained.
What we have here is an introduction to the wonderful world of quantum computers. Usefully, Gribbin leads us in through conventional computing, with workmanlike short biographies of Turing and von Neumann to help make the route to understanding what is going on in devices we use every day, but of which we have little comprehension, much clearer. It’s good to have a computing history that fully takes into account the British contribution, often sidelined by US work, in part because of the way Churchill unfortunately insisted that most of the UK wartime work be destroyed.
The second section of the book takes us into quantum theory, using Richard Feynman and John Bell as the key biographies, while the third concentrates on quantum computing, leading on the perhaps rather less obviously central character of David Deutsch and taking us through some of the many mechanisms for building a quantum computer that are currently being worked on.
Overall this works very well, and we get a powerful insight into the capabilities of this remarkable technology and the huge challenges that are faced in making it work reliably. To get any idea of how quantum computers work it is necessary to give a good background in quantum theory itself, and this is something that Gribbin can do with one hand tied behind his back. It is indicative of the strange nature of quantum theory that when writing on the subject, I take a very different line on some aspects – notably the many worlds interpretation – and yet both views are currently unassailable. You might even say superposed.
If I have any criticism it is that some areas are brushed over just a little too lightly – this isn’t the book to really get a total low-down on quantum physics as it isn’t its central topic. This means that there are a few places were Gribbin effectively says ‘this happens, but you don’t need to understand it.’ The only specific topic I do think could have been handled better is the very important concept of decoherence, which (unless I missed it) is introduced without ever explaining what it means. Certainly in the first reference to it in the index it is used as if it is obvious what it’s about. Yet in reality it is a subtle concept that is hugely important to the quantum computing business. I really wish there had been a few pages putting this straight.
Overall, without doubt the best book I’ve read to provide the general reader with an introduction to quantum computers, and given their potential importance in the future, that has to make it a brilliant addition to any popular science enthusiast’s shelf.
Hardback:  
Kindle:  
Review by Brian Clegg

Comments

Popular posts from this blog

The Great Silence – Milan Cirkovic ****

The great 20th century physicist Enrico Fermi didn’t say a lot about extraterrestrial life, but his one utterance on the subject has gone down in legend. He said ‘Where is everybody?’ Given the enormous size and age of the universe, and the basic Copernican principle that there’s nothing special about planet Earth, space should be teeming with aliens. Yet we see no evidence of them. That, in a nutshell, is Fermi’s paradox.

Not everyone agrees that Fermi’s paradox is a paradox. To some people, it’s far from obvious that ‘space should be teeming with aliens’, while UFO believers would scoff at the suggestion that ‘we see no evidence of them’. Even people who accept that both statements are true – including  a lot of professional scientists – don’t always lose sleep over Fermi’s paradox. That’s something that makes Milan Cirkovic see red, because he takes it very seriously indeed. In his own words, ‘it is the most complex multidisciplinary problem in contemporary science’.

He points out th…

The Order of Time - Carlo Rovelli ***

There's good news and bad news. The good news is that The Order of Time does what A Brief History of Timeseemed to promise but didn't cover: it attempts to explore what time itself is. The bad news is that Carlo Rovelli does this in such a flowery and hand-waving fashion that, though the reader may get a brief feeling that they understand what he's writing about, any understanding rapidly disappears like the scent of a passing flower (the style is catching).

It doesn't help either that the book is in translation so some scientific terms are mangled, or that Rovelli has a habit of self-contradiction. Time and again (pun intended) he tells us time doesn't exist, then makes use of it. For example, at one point within a page of telling us of time's absence Rovelli writes of events that have duration and a 'when' - both meaningless terms without time. At one point he speaks of a world without time, elsewhere he says 'Time and space are real phenomena.'…

The Happy Brain - Dean Burnett ****

This book was sitting on my desk for some time, and every time I saw it, I read the title as 'The Happy Brian'. The pleasure this gave me was one aspect of the science of happiness that Dean Burnett does not cover in this engaging book.

Burnett's writing style is breezy and sometimes (particularly in footnotes) verging on the whimsical. His approach works best in the parts of the narrative where he is interviewing everyone from Charlotte Church to a stand-up comedian and various professors on aspects of happiness. We get to see the relevance of home and familiarity, other people, love (and sex), humour and more, always tying the observations back to the brain.

In a way, Burnett sets himself up to fail, pointing out fairly early on that everything is far too complex in the brain to really pin down the causes of something as diffuse as happiness. He starts off with the idea of cheekily trying to get time on an MRI scanner to study what his own brain does when he's happy, b…