http://www.discovery.com/news/briefs/20010118/te_light.html

Scientists Bring Light to Stop

By Discovery.com News

Jan. 18, 2001 - Researchers have stopped light in its tracks, then released it again, a feat that could ultimately accelerate the speed of computing.

Two independent teams of physicists reined in light, reports Thursday's New York Times. One team was led by Lene Vestergaard Hau of Harvard University and the Rowland Institute for Science in Cambridge, Mass., and the other by Ronald L. Walsworth and Mikhail D. Lukin of the Harvard-Smithsonian Center for Astrophysics, in Cambridge.

A paper by Walsworth, Lukin and three collaborators, all at Harvard- Smithsonian, is scheduled to appear in the Jan. 29 issue of Physical Review Letters, according to the Times.

The speed of light is 186,000 miles per second. Water, glass and crystal slow the speed of light a little, an effect that bends light rays, allowing, for example, lenses to focus.

Using a related effect, the Walsworth-Lukin team stopped the light in containers of gas. In this medium, the light became fainter and fainter, then slowed, then stopped. A second light flashed through the gas revived the original beam, reports the Times.

The light then exited the chamber with nearly the same properties it had when it entered. Hau got similar results with her closely related techniques.

"Essentially, the light becomes stuck in the medium, and it can't get out until the experimenters say so," Seth Lloyd, an associate professor of mechanical engineering at the Massachusetts Institute of Technology who is familiar with the work, told the Times.

Lloyd added, "Who ever thought that you could make light stand still?"

He said the biggest impact of the experiments could come in quantum computing and quantum communication. Both concepts rely heavily on the ability of light to carry "quantum" information - particles that can exist in many places or states at once.

Quantum computers, which currently exist only in theory, could accomplish certain operations much faster than existing machines. For such computers, light is needed to form large networks of computers. But the light must be stored - at least temporarily - a difficult problem that the new work could help solve.

-- (Qu@ntum.information), January 21, 2001

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Ja, diss ist not OK. Gott nein play dice mit der universe.

-- (AlEinstein@Princeton.edu), January 21, 2001.