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

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F15%3A00226131" target="_blank" >RIV/68407700:21340/15:00226131 - isvavai.cz</a>
Result on the web
<a href="http://www.sciencemag.org/content/347/6224/857.abstract" target="_blank" >http://www.sciencemag.org/content/347/6224/857.abstract</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1126/science.aaa3035" target="_blank" >10.1126/science.aaa3035</a>

Result language
angličtina
Original language name
Spatially structured photons that travel in free space slower than the speed of light
Original language description
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 wave vectors 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 in 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 ~1 meter. Our work highlights that, even in free space, the invariance of the speed of light only applies to plane waves.
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BH - Optics, masers and lasers
OECD FORD branch
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Publication year
2015
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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