Science: Hey Presto! the Quantum Supercomputer ; Mythical Cats in Boxes? Time Travel? How about Computers as Powerful as the Universe? We're Talking Quantum Physics. and Now the Technology Is with Us
Gribbin, John, The Independent (London, England)
Quantum physics used to be exotic science. It is now technology. That doesn't mean that we understand it - as Richard Feynman, one of the greatest quantum mechanics, was fond of saying, "nobody understands quantum physics". Don't try to understand how the quantum world can be the way it is, he urged; just lie back and enjoy it.
It means that engineers have learnt how to manipulate quantum entities, such as single atoms, using the same kind of empirical, suck-it-and-see approach that enabled engineers to design effective steam engines long before the laws of thermodynamics were worked out. One of those engineers, Terry Clark, of the University of Sussex, believes that as a result we stand on the threshold of a new age of technological advance, where Arthur C Clarke's adage "any sufficiently advanced technology is indistinguishable from magic" will come true before our very eyes.
It isn't just Terry Clark who thinks the quantum revolution is at hand. His team has just received major recognition in the form of funding from the new National Endowment for Science, Technology and the Arts - one of just eight such awards made in the first year of its existence. The aim of the team is to develop machines operating according to quantum mechanics rather than Newtonian mechanics.
"This could lead to dramatic revolutions in technology in the next century, at least on a par with those we have experienced this century," says Clark. To give some idea just how dramatic, this includes the possibility of teleportation (not quite Star Trek style, but transporting particles from one place to another instantaneously). That, however, may lie a decade or two down the line.
Right now, though, one of the key areas in which this revolution is developing is in the field of computers, with the prospect of quantum computers millions of times more powerful than any machine available today. But anyone familiar with computers may be startled to learn that one reason for all the excitement, according to the Oxford-based quantum physicist David Deutsch, is that we already have the technology to build a four-bit quantum computer. In case you need reminding, four bits - four binary digits - correspond to just half a byte, in the familiar terminology.
The excitement arises because the computer in question operates on quantum- mechanical principles, not in line with the physics of everyday common sense. Which makes a quantum computer, in principle, almost unimaginably more powerful than its conventional counterpart.
The best way to get a handle on this is to look closely at those individual bits. A computer bit is just an on-off switch that can exist in either of two states, so that a string of bits can be represented as a string of zeros and ones in binary code. But the "switches" used in quantum computers behave in a significantly different way. They are called "qbits", and they behave rather like Schrodinger's famous cat. This is where Feynman's exhortation to "lie back and enjoy it" comes in. What you are about to read may be weird, but it really is the way the quantum world works - and nobody, not even Feynman, has ever understood how it can be like that, so you are in good company.
Erwin Schrodinger, one of the quantum pioneers, came up with his theoretical puzzle in the Thirties, to demonstrate what he saw as the unacceptable face of quantum physics. The eponymous feline is imagined to be locked in a box with a quantum device that has a 50:50 chance of triggering the cat's death. According to all the equations of quantum mechanics (including, to his intense disgust, the ones discovered by Schrodinger himself), quantum entities such as atoms do not "decide" what state they are in until they interact with something, or somebody measures them. By imagining a quantum trigger to decide the fate of the cat, Schrodinger scaled this quantum indecisiveness up to a human (or feline) level. …