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Researchers stop light, aiding quantum computing goals

Posted: 17 Dec 2003 ?? ?Print Version ?Bookmark and Share

Keywords:laser light? sodium ions? quantum computers?

Two years ago, Harvard University researchers shined a pulse of laser light through a cloud of super-cold sodium ions and slowed the light to about 38 mph. Another group of Harvard physicists have brought light from its normal speed of 186,000 miles per second to zero.

Researchers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, were able to bring a light pulse measuring a half mile long to a complete stop before allowing it to continue. Light entered a chamber a fraction of an inch wide, and was sufficiently slowed by metal atoms for the entire beam to enter the chamber before allowing it to exit.

Observers said the feat could speed development of quantum computers.

Researchers cooled the metal atoms to just above absolute zero. Then they shut off the coupling beam of a tuned coupling-beam laser when the entire light pulse entered the chamber, stopping the beam for as long as a millisecond before turning the coupling beam back on and allowing the light pulse to continue at its full speed.

Using these techniques and others, quantum computer developers could perform calculations much faster using light. Making such calculations would require that the information contained in a light pulse be stored, a major technical hurdle since light is intrinsically elusive.

- Nicolas Mokhoff

EE Times





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