Harvard University

Slow Light – Lene Vestergaard Hau, Harvard University

Ultra-slow light in Bose-Einstein condensates: Shocking matter and transforming light.

Lene Vestergaard Hau
Lyman Laboratory, Harvard University

Light pulses have been slowed in a Bose-Einstein condensate to only 17 m/s, more than seven orders of magnitude lower than the light speed in vacuum. 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 1-2 miles long in vacuum, is compressed to a size of ~50 microns, and at that point it is completely contained within the atom cloud. This further allows the light pulse to be completely stopped and stored in the atomic medium for up to several milliseconds, and subsequently regenerated with no loss.

With the most recent extension of the method, the light roadblock, light pulses have been compressed from 2 miles to only 1-2 microns. The system has been used to generate Quantum Shock Waves in Bose-Einstein condensates. These dramatic excitations result in the formation of solitons and quantized vortices: the superfluid analogue of tornadoes. The vortices are created far out of equilibrium, in pairs of opposite circulation, and the observations reveal directly the process of superfluid breakdown.

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