Physicists say they have brought light to a complete halt for a fraction of a second and then sent it on its way, an achievement that could someday help scientists develop powerful new computers.

The research differs from work published in 2001 that was hailed at the time as having brought light to standstill.

In that work, light pulses were technically "stored" briefly when individual particles of light, or photons, were taken up by atoms in a gas.

Harvard University researchers have now topped that feat by truly holding light and its energy in its tracks -- if only for a few hundred-thousandths of a second.

"We have succeeded in holding a light pulse still without taking all the energy away from it," said Mikhail D. Lukin, a Harvard physicist.

Harnessing light particles to store and process data could aid the still distant goal of so-called quantum computers, as well as methods for communicating information over long distances without risk of eavesdropping.

The research may also have applications for improving conventional fiber-optic communications and data processing techniques that use light as an information carrier. Lukin said the present research is just another step toward efforts to control light, but said additional work is needed to determine if it can aid these applications.

The findings appear in Thursday's issue of the journal Nature.

Stanford University physicist Stephen Harris said the new research is promising and represents an important scientific first.

Matthew Bigelow, a scientist at the University of Rochester involved in light research, called the new study "very clever" and something that may ultimately spur the development of superior light-based computers.

"I think it's moving us in the right direction," he said.

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