Fast causal information transmission in a medium with a slow group velocity

Michael D. Stenner, Daniel J. Gauthier, Mark A Neifeld

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It is widely believed that the velocity of information νi encoded on an optical pulse is equal to the group velocity νg, at least when νg is less than the speed of light in vacuum c. On the other hand, several authors suggest that νi = c, although the size of the signal traveling at this velocity may be small, thereby making it difficult to measure. Here, we measure νi for pulses propagating through a resonant "slow-light" medium where νg ≈ 0.006c. We find νi ≈ 1.03c-0.25c+0.49c, or that νi χ 168νg clearly demonstrating that the speed of information cannot be generally described by νg, but is characterized by its own velocity.

Original languageEnglish (US)
Article number053902
JournalPhysical Review Letters
Issue number5
Publication statusPublished - Feb 11 2005


ASJC Scopus subject areas

  • Physics and Astronomy(all)

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