Quantum optics: Speed of light, zero

In a remarkable experiment reported in this issue, resonant probe laser pulses are brought to a complete stop in a magnetically trapped cold cloud of sodium atoms, simultaneously illuminated by a second coupling laser. When the coupling laser is turned off the compressed probe pulse is effectively stopped and the coherent information contained in the laser fields is 'frozen' in the atomic medium for up to 1 ms. Turn the coupling laser back on and the probe pulse is regenerated and the stored coherence read out. Stopping light in this way is no party trick: it has the potential to be developed into a form of quantum information processing.

Observation of coherent optical information storage in an atomic medium using halted light pulses
CHIEN LIU, ZACHARY DUTTON, CYRUS H. BEHROOZI, LENE VESTERGAARD HAU
Nature 409, 490-493 (25 January 2001)
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Stopping light in its tracks
ERIC A. CORNELL
Using lasers and ultracold atoms, physicists have found a way to stop and start a pulse of light. This magic trick may one day be used to store data in a quantum computer.
Nature 409, 461-462 (25 January 2001)
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Freezing light
In 1999, Hau et al. reported in Nature that they had slowed light from its normal 300 million metres per second to just 17 metres per second. Now they have gone even further and stopped it completely. The discovery could be big news for optical and quantum computing. (25 January 2001)

physics: Stop that light beam, I want to get off
How do you catch a wave and pin it down � especially when it is moving at the speed of light? (25 January 2001)

25 January 2001 table of contents