THEY said it couldn’t be done. They said it would never be practical. They were wrong, says David Deutsch.
He is referring to the quest to build a quantum computer. This machine would exploit the weird properties of quantum mechanics to perform tasks millions of times faster than today’s most powerful supercomputers. Such a device – if we can build one – would overturn the field of cryptography and revolutionise the computer industry. Yet despite this glittering prize, researchers have so far only coaxed quantum systems into solving mathematics problems that children can do in their heads.
Deutsch, a University of Oxford physicist who drew up the first blueprint for a quantum computer in 1985, thought we were still 20 years away from a useful device – until last summer. That was when theorist Simon Benjamin, also at Oxford, told him about cluster states, an approach that Benjamin believed could solve the major hang-ups that have plagued the quantum community. The idea redefines how a quantum computer processes information, and takes care of the trickiest bits of the calculation first. It should also scale up much more easily than previous designs, allowing researchers to perform larger and larger computations. The chat with Benjamin changed Deutsch’s vision; after two decades of pushing back predictions, he now sees a practical quantum computer arriving within 10 years. “He gave me the zeal of a convert,” says Deutsch.
A practical quantum computer is now less than 10 years away
The advantage of a quantum computer over its classical counterpart has long put a gleam in the eye of physicists. Conventional computers represent information as bits, which have…