A team of Silicon Valley researchers have turned molecules of chloroform into the world’s first quantum computer.
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The breakthrough uses a variation of medicine’s magnetic resonance imaging to manipulate the core of two elements in chloroform–carbon and hydrogen. By doing so, the researchers were able to perform a simple database query at the molecular level.
A quantum computer has the advantage of being blindingly fast and could prove thousands or even millions of times faster than anything in use today. Any practical application is many years away.
“This will reshape the face of science,” said Stanley Williams, a Hewlett-Packard Co. physicist who is coordinating his company’s quantum computing research in Palo Alto but was not part of the discovery team.
The development takes computing a step away from the stable, binary world of silicon with its ones and zeros, toward the bizarre world of quantum physics, where reality sometimes seems to defy logic. In the quantum world, a particle is neither a one nor a zero–it’s both.
The study of quantum physics has taught researchers the arcane rules of the subatomic road. Trying to describe these rules to the uninitiated, theorists inevitably use the word “counter-intuitive”–one way of saying they just don’t make sense.
For example, in our world, you can only be in one place at one time and particles are simply bits of matter.
But in the quantum world, elementary particles can be in every possible place at the same time.
Because a quantum computer does its figuring in the subatomic world, it could take a question and examine all possible answers–the right ones and the wrong ones–virtually at once. That explains the lightning speed.
“It is very exciting,” said Isaac Chuang of IBM’s Almaden Research Center in San Jose, who was part of the successful team. “But I want to emphasize it is still basic research.”
The problem solved by the quantum computer–finding a piece of data from four possible answers–would be trivial for any ordinary computer. But the way the researchers’ quantum computer did it was impossible by conventional computing.
A standard computer would analyze each of the four possibilities, one after the other, until it found the answer. On average, it would take the standard computer two and a quarter tries. The quantum computer analyzes all four possible answers with a single query.
“You can be in four places at the same time,” Chuang said.
Two years ago, many researchers thought the latest accomplishment was impossible. The problem was maintaining the molecule in a coherent state long enough to do the computing.
“The trick of making a quantum computer is being able to understand these strange rules of physics and being able to map your problem onto these strange rules,” said Chuang.
Chuang and Neal Gershenfeld, a physicist at the Massachusetts Institute of Technology, developed a way to do this, working with researchers at MIT, Oxford University, the University of California at Berkeley and Stanford.
The researchers used nuclear magnetic resonance techniques to study the structure of the molecule and control the orientation of its nucleus before manipulating it with a radio wave. “We represent a zero and one by the state of a nucleus, the nuclear spin,” said Chuang. “Is the spin pointing up or is it pointing down?”
The spin can also be halfway between zero and one, a fact that gives quantum computing so much more potential power.