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Frozen light
Article By:
Vestergaard Hau, Lene Lyman Laboratory, Department of Physics, Harvard University, Cambridge, Massachusetts.
Last reviewed:2003
DOI:https://doi.org/10.1036/1097-8542.YB030100
Ultraslow light was first observed by L. V. Hau and her colleagues in 1998. Light pulses were slowed in a Bose-Einstein condensate of sodium to only 17 m/s (38 mi/h), more than seven orders of magnitude lower than the light speed in vacuum. In later experiments, light pulse velocities as low as 50 cm/s (1.1 mi/h) were observed. This method was brought to its logical extreme when light pulses were completely stopped and stored in an atomic medium for up to several milliseconds. Associated with the dramatic reduction factor for the light speed is a spatial compression of the pulses by the same large factor. A light pulse, which is 2–3 km (1–2 mi) long in vacuum, is compressed to a size of about 50 micrometers, and at that point it is completely contained within the condensate.
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