New "slow light" paper

  • #1
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Hi,

this experiment has been doing it's rounds in the media this week. I've read the popular explanations and the preprint but as a layman I'm not sure I quite get what they've done. Especially I don't get how the spatial distribution of a photon affects its propagation speed. Or in what sense a photon has a spatial distribution.


Spatially structured photons that travel in free space slower than the speed of light

Abstract:
That the speed of light in free space is constant is a cornerstone of modern physics. However, light beams have finite transverse size, which leads to a modification of their wavevectors resulting in a change to their phase and group velocities. We study the group velocity of single photons by measuring a change in their arrival time that results from changing the beam’s transverse spatial structure. Using time-correlated photon pairs we show a reduction of the group velocity of photons in both a Bessel beam and photons in a focused Gaussian beam. In both cases, the delay is several micrometers over a propagation distance of the order of 1 m. Our work highlights that, even in free space, the invariance of the speed of light only applies to plane waves.​

http://www.sciencemag.org/content/early/2015/01/21/science.aaa3035 (not free)

Preprint can be found here: http://arxiv.org/abs/1411.3987
 

Answers and Replies

  • #3
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Doh, I searched for both the arXiv code and parts of the paper title and didn't find it :(
 

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