Quantum communication: atoms talk long distance

An image released by Yale University's Schoelkopf Lab on September 26, 2007 shows a microchip that enables quantum information to be shuttled back and forth between two superconducting qubits.

CHICAGO (Reuters) - U.S. physicists have coaxed tiny artificial atoms into communicating in an advance that may lead to super-fast quantum computers, the researchers said on Wednesday.

Quantum computers hold the promise of being enormously powerful, capable of solving in seconds problems that take today's fastest machines years to crack.

So far, physicists have worked mostly on developing the most basic of elements that can store information known as quantum bits, or qubits.

But a series of papers in the journal Nature suggest researchers have found a way to get these qubits to communicate over a distance, for instance, across a computer chip.

In the past, the best qubits could do was talk to neighboring qubits, much like the childhood game of telephone.

But researchers from Yale University have found a way to move information stored in a stationary quantum bit via a microwave photon to another stationary quantum bit on the same chip.

"That is the most elementary step in building and operating a quantum computer," said Yale physics professor Steve Girvin in a telephone interview.

"It's a small step. It's only two qubits," Girvin said. "But it is a non-trivial step towards this very difficult goal of building a quantum computer."

Researchers at the National Institute of Standards and Technology, a part of the U.S. Department of Commerce, described a similar feat in a separate paper in Nature.

They repeatedly transferred quantum information between two qubits on a tiny cable.

This technique also gave the qubits more staying power. Normally, qubits maintain the same state for only half a microsecond.

Quantum computers must take advantage of the unusual rules of quantum mechanics, the principles that govern nature's smallest particles.

"Quantum information is much more delicate than classical information, but much more powerful," Girvin said.

"It is the delicate part that we have to be good engineers to deal with so we can take advantage of the much more powerful part," he said.