Shortcut through Time
George Johnson
$24/£17.99 Knopf/Jonathan Cape
MIGHT the computer on your desk one day be as obsolete as an abacus? Yes,
if quantum computers ever reach their full potential. Their critical
components would be just short strings of atoms, but thanks to the
subtleties of quantum mechanics they'd have phenomenal power. To achieve
the performance of a 13-atom quantum computer, one of today's
state-of-the-art supercomputers would need to cover 5000 times the
surface area of the Earth.
As ace science writer George Johnson from The New York Times
explains in this lucid and accessible book, the nittty-gritty workings of
such a computer depend on the subtleties of quantum mechanics. A quantum
computer exploits the fact that each atom in its string can be in a
"superposition" of several states simultaneously, for example,
spin up and spin down states. This brings an awesome number of potential
combinations to bear on a calculation. Computations are performed on the
string of atoms by probing their states with radiation of carefully
chosen energies.
Johnson does a fine job of telling a story that makes sense both to those
who are completely at home in the mathematical theory of the subatomic
world and to those whose reaction to the theory is abject terror. He
leavens the tale with a generous amount of human interest, telling us how
physicist Richard Feynman started it all in the early 1980s, and how a
host of others in Europe and the US have gradually turned a promising
concept into a practical possibility.
But there is a glitch: the thinking about the software of these computers
has rapidly outpaced progress in the hardware. Although the first
primitive quantum computers were built in the 1990s, we are a very long
way from building one that achieves the technology's full potential. It
is, however, possible to envisage a quantum computer that can handle
tasks that are way beyond today's conventional PCs, such as factoring
huge numbers, explaining the folding of proteins and debugging complex
software. Even if these dreams are never realised, quantum mechanics is
likely to have at least one powerful industrial application - setting up
truly uncrackable codes.
A Shortcut through Time gently introduces this and other themes in
the field with a beguiling combination of clarity and enthusiasm.
Graham Farmelo is a physicist
Available in Britain in April, ISBN 0224062336
http://www.newscientist.com/opinion/opbooks.jsp?id=ns23883
