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Review - The Quest for the Quantum Computer - Julian Brown


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There's a paradox at the heart of the story this book tells. We know, and have known for a good number of years now, that a quantum computer can do all sorts of handy things. It can crack the powerful RSA computer encryption algorithm (we didn't say they were all positive handy things). It can vastly speed up a search through an unstructured database. It can calculate with limitless accuracy (sort of). The only problem is, no one knows how to build one.

Julian Brown does a good job of telling the story of this strange two speed race. The theory of what could be done with a quantum computer - where each quantum bit (qubit) is a quantum object like a photon, electron or atom - far outstrips the realities that are so far possible (though there have been a couple of steps forward taken on the experimental side since Brown wrote the book).

If you are either versed in quantum theory to undergraduate level, or a computer science undergraduate I have no qualms in saying that this is brilliant book I'd highly recommend, and it deserves five stars. But for the rest of the potential readership there are some issues.

It's fair to say that Brown spends too much time and detail ploughing through the technical details for the general reader, and it's easy to get lost in a cloud of unnecessary complexity. Just occasionally this becomes downright boring. It's also true that there's a partisan flavour that might be misleading to anyone not familiar with the arguments on quantum interpretation. Brown is strongly influenced by British physicist David Deutsch and his multiverse interpretation of quantum theory (hence the US edition's more realistic title: Minds, Machines and the Multiverse). This idea, roughly that at each quantum change the universe forks into two states, meaning that there are many (many!) near-identical copies of the universe has been Deutsch's leading light for a long time - and it's anything but undisputed.

While the theory has to be mentioned to explain one of the origins of the concept of quantum computing, there is no need to employ it further down the line, and I think Julian Brown causes extra confusion by doing so.

Nonetheless, this is a very good book about a wonderfully strange subject. Rather like Hawking's A Brief History of Time, if you are prepared to suspend any lack of understanding and let it wash over you, it's a good read, and there's enough human detail in there to give it an edge. It's just a shame that, while recognizing David Deutsch's immense contribution to the quantum computing arena, Brown couldn't have remained a little less enthusiastic about the multiverse.

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Reviewed by Brian Clegg


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Last update 05 June 2007