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For The Week Of July 15, 2003
Light Speed Experiments Promise Great Things
A series of scientific experiments during the past decade have shown incredible success in manipulating photons - even to the point of stopping and restarting light. Most recently, researchers have not only stopped light, but have done so at room temperature, promising to revolutionize quantum computing and telecommunications.
Light travels at 186,282 miles per second in a vacuum. However, when traveling through various media, such as glass or gasses or crystals, light can slow down significantly. In 1999, experiments slowed a pulse of light to an incredibly sluggish 38 miles per hour in a magnetically trapped super-cooled cloud of sodium atoms. Then, using a similar technique in 2001, these scientists brought a light pulse to a brief but complete stop.
These experiments, however, depended on the extremely cold state of the cloud of sodium atoms. Now, researchers at the University of Rochester, NY claim to have significantly slowed a pulse of light at room temperature using specially treated crystals of alexandrite.
The practical applications for this technology are far-reaching. Because photons, naturally, travel at light speed, researchers have sought to use photons as the next generation of information carriers. Quantum computing uses the quantum states of atoms and photons as bits of information. Yet, photons are far more difficult to 'store' than electrons, and so have a poor memory. If photons could be stopped and stored, they would retain the information they carry for a longer time.
However, it is difficult to mass-produce clouds of sodium atoms cooled to just 5 degrees above absolute zero. The Rochester team's experiments are encouraging because they are able to produce their results at room temperature, offering many potential practical applications in optical communications and quantum computers.
• Light Manipulated at Room Temp - MSNBC
• Scientists Discover a New Way to Slow Speed of Light - CS Monitor
• Quantum Optics: Speed of Light, Zero - Nature
• Freezing Light - Nature
• Einstein's Relativity Theory Hits a Speed Bump - The Age