Gain-assisted superluminal light propagation

@article{Wang2000GainassistedSL,
  title={Gain-assisted superluminal light propagation},
  author={L. J. Wang and Alex Kuzmich and Arthur Dogariu},
  journal={Nature},
  year={2000},
  volume={406},
  pages={277-279}
}
Einstein's theory of special relativity and the principle of causality imply that the speed of any moving object cannot exceed that of light in a vacuum (c). Nevertheless, there exist various proposals for observing faster-than- c propagation of light pulses, using anomalous dispersion near an absorption line, nonlinear and linear gain lines, or tunnelling barriers. However, in all previous experimental demonstrations, the light pulses experienced either very large absorption or severe… 
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