First solid-state quantum processor created

WASHINGTON, June 28 (Xinhua) -- U.S. researchers said Sunday they had created the first rudimentary solid-state quantum processor and used the super conducting chip to successfully run elementary algorithms.

The findings, which appeared Sunday in Nature's advanced online publication, are seen as another step toward the ultimate dream of building a quantum computer.

"Our processor can perform only a few very simple quantum tasks, which have been demonstrated before with single nuclei, atoms and photons," said Professor Robert Schoelkopf of Yale University.

"But this is the first time they've been possible in an all-electronic device that looks and feels much more like a regular microprocessor," Schoelkopf said.

Unlike regular processors, which store information in the form of digital bits that each possess a value of either 0 or 1, quantum processor use qubits, or quantum bits, which can hold values of 0 and 1 at the same time.

Qubits in this "superposition" of both values may allow many more calculations to be performed simultaneously than is possible with traditional digital bits, thus allowing for greater information storage and processing power.

The Yale team made their device out of two qubits, each of which is actually made up of a billion aluminum atoms.

The device processed a simple search algorithm, also known as the reverse phone book search, where someone's number is known but not the name. The processor essentially reads all the numbers in the phone book at once to find the right number.

"Instead of having to place a phone call to one number, then another number, you use quantum mechanics to speed up the process," Schoelkopf said. "It's like being able to place one phone call that simultaneously tests all ... numbers, but only goes through to the right one."

These sorts of computations, though simple, have not been possible using solid-state qubits until now in part because scientists could not get the qubits to last long enough.

While the first qubits a decade ago were able to maintain specific quantum states for about a nanosecond, Schoelkopf and his team are now able to maintain theirs for a microsecond -- a thousand times longer, which is enough to run the simple algorithms.

To perform their operations, the qubits communicate with one another using a "quantum bus"-- photons that transmit information through wires connecting the qubits -- previously developed by the Yale group.

Next, the team will work to increase the time the qubits maintain their quantum states so they can run more complex algorithms. They will also work to connect more qubits to the quantum bus.

The processing power increases exponentially with each qubit added, Schoelkopf said, so the potential for more advanced quantum computing is enormous.

But he cautions it will still be some time before quantum computers are being used to solve complex problems. "We're still far away from building a practical quantum computer, but this isa major step forward."