Breakthrough in large-scale quantum computing

Last Updated: Sun, Oct 21, 2012 08:20 hrs

Washington, Oct 21 (IANS) Researchers have worked out a process that may permit quick and reliable transfer of quantum information through a computer.

Developed by Princeton University team led by physicist Jason Petta, the process could eventually allow engineers to build large scale quantum computers with the help of millions of quantum bits or qubits.

So far, researchers have only been able to manipulate small numbers of qubits, not enough for a practical machine, the journal Nature reports.

"The whole game at this point in quantum computing is trying to build a larger system," said Andrew Houck, assistant professor of electrical engineering, member of the research team, according to a Princeton University Engineering School statement.

To facilitate transfer, Petta's team used a stream of microwave photons (light atoms) to analyse a pair of electrons trapped in a tiny cage called a quantum dot.

The "spin state" of the electrons - information about how they are spinning - serves as the qubit, a basic unit of information.

The microwave stream allows the scientists to read that information.

The distances involved are very small; the entire apparatus operates over a little more than a centimetre. But on the subatomic scale, they are vast. It is like coordinating the motion of a top spinning on the moon with another on the surface of the earth.

"It's the most amazing thing," said Jake Taylor, physicist at the National Institute of Standards and Technology and the Joint Quantum Institute at the University of Maryland, who worked on the project with the Princeton team.

"You have a single electron almost completely changing the properties of an inch-long electrical system."

"The point of a quantum computer is not that they can do what a normal computer can do but faster; that's not what they are," said Houck.

"The quantum computer would allow us to approach problems differently. It would allow us to solve problems that cannot be solved with a normal computer," he added.

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