[General] Light with "self-torque"

[Richard Gauthier]

Hi Dan,
   Thanks for your note about this discovery of a new property of light, “self-torque"



which is reminiscent of the superluminal double-helix model of the photon, though with clearly significant differences.



all the best,
       Richard

> On Jun 29, 2019, at 2:56 AM, DataPacRat <datapacrat at gmail.com> wrote:
> 
> An article I believe is of interest to the members of this list:
> 
> https://phys.org/news/2019-06-property.html
> 
>> New property of light discovered
>> by Bob Yirka, Science X Network, Phys.org
>> 
>> A team of researchers affiliated with several institutions in Spain and the U.S. has
>> announced that they have discovered a new property of light—self-torque. In their paper
>> published in the journal Science, the group describes how they happened to spot the new
>> property and possible uses for it.
>> 
>> Scientists have long known about such properties of light as wavelength. More recently,
>> researchers have found that light can also be twisted, a property called angular
>> momentum. Beams with highly structured angular momentum are said to have orbital
>> angular momentum (OAM), and are called vortex beams. They appear as a helix
>> surrounding a common center, and when they strike a flat surface, they appear as
>> doughnut-shaped. In this new effort, the researchers were working with OAM beams
>> when they found the light behaving in a way that had never been seen before.
>> 
>> The experiments involved firing two lasers at a cloud of argon gas—doing so forced the
>> beams to overlap, and they joined and were emitted as a single beam from the other side
>> of the argon cloud. The result was a type of vortex beam. The researchers then
>> wondered what would happen if the lasers had different orbital angular momentum and if
>> they were slightly out of sync. This resulted in a beam that looked like a corkscrew with a
>> gradually changing twist. And when the beam struck a flat surface, it looked like a
>> crescent moon. The researchers noted that looked at another way, a single photon at the
>> front of the beam was orbiting around its center more slowly than a photon at the back of
>> the beam. The researchers promptly dubbed the new property self-torque—and not only
>> is it a newly discovered property of light, it is also one that has never even been
>> predicted.
>> 
>> The researchers suggest that it should be possible to use their technique to modulate the
>> orbital angular momentum of light in ways very similar to modulating frequencies in
>> communications equipment. This could lead to the development of novel devices that
>> make use of manipulating extremely tiny materials.
> 
> The actual published article is at
> https://arxiv.org/ftp/arxiv/papers/1901/1901.10942.pdf . Discovered
> via the blog article at
> https://science.slashdot.org/story/19/06/29/0039231/new-property-of-light-discovered
> , where one comment links to
> https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0056086
> , which includes the conclusion "In conclusion, twisted waves cannot
> carry information that is independent from the information contained
> in plane wave modes at the same frequency."
> 
> 
> Thank you for your time,
> --
> Dan Boese, aka DataPacRat
> "Does aₘᵢₙ=2c²/Θ ? I don't know, but wouldn't it be fascinating if it were?"
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