New property of light discovered

light beam
Credit: CC0 Public Domain

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 . Beams with highly structured angular momentum are said to have orbital angular momentum (OAM), and are called . 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 , it looked like a crescent moon. The researchers noted that looked at another way, a at the front of the beam was orbiting around its center more slowly than a photon at the back of the . 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.

A new property of light beams, the self-torque of light, which is associated to a temporal variation of the orbital angular momentum. Extreme-ultraviolet ultrafast pulses with self-torque are generated through high harmonic generation. Credit: JILA (USA) Rebecca Jacobson, Servicio de Produccion e Innovacion Digital – Universidad de Salamanca (Spain)

The researchers suggest that it should be possible to use their technique to modulate the 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.


Explore further

Multicolored light twists in new knotted ways

More information: Laura Rego et al. Generation of extreme-ultraviolet beams with time-varying orbital angular momentum, Science (2019). DOI: 10.1126/science.aaw9486
Journal information: Science

© 2019 Science X Network

Citation: New property of light discovered (2019, June 28) retrieved 21 October 2019 from https://phys.org/news/2019-06-property.html
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Jun 28, 2019
And Lagrangian cycles still describe the discrete features needed to represent any particular phase.... yeah, new!

Jun 28, 2019
It's almost as if the photon is comprised of two massless particles.

Jun 28, 2019
It's almost as if the photon is comprised of two massless particles.

Or one longer particle with the front losing its rotational energy faster than the back.
Or a pair of waves situated at 90 degrees to each other winding along a common axis.
Or a vibrating string entangled with other vibrating strings.
Or...

It is the refinement of ways to test these theories that is the most cool.

Jun 28, 2019
You call 'em vortexes - I call 'em gyres... :-)

Jun 28, 2019
Actually that's "vortices."

Jun 28, 2019
Meanwhile, quanta like photons can have two types of angular momenum: OAM and SAM. Orbital angular momentum and spin angular momentum. This article does a very bad job of differentiating between them. Together they add up to TAM: total angular momentum. And TAM is a conserved quantity.

Do better, physorg. You guys are having a bad month.

Jun 28, 2019
Meanwhile, quanta like photons can have two types of angular momenum: OAM and SAM. ....

Do better, physorg. You guys are having a bad month.


You forgot no angular momentum, you know for spherical harmonics
;)

Jun 28, 2019
I don't see what spherical harmonics have to do with the propagation of a single photon. Maybe you can explain it; most likely it will be a word salad.

Jun 28, 2019
You call 'em vortexes - I call 'em gyres... :-)


I like it!

Jun 28, 2019
I don't see what spherical harmonics have to do with the propagation of a single photon. Maybe you can explain it; most likely it will be a word salad.

See his spaced out comment in this article....
https://phys.org/...ity.html

Jun 28, 2019
Actually that's "vortices."

Actually, vortexes is also correct.

Jun 28, 2019
And Lagrangian cycles still describe the discrete features needed to represent any particular phase.... yeah, new!


Yes, new physics, not old math. Why delve into local so called orbifold constructions (i.e. "fold" or take the quiotient space of R^n by some finite group action - essentially here take the spin of photons) when the physicists use OAM to construct observable chirps? (I take it "Lagrangian cycles" refers to the orbifolds that makes sense.)

I can represent phase by taking the second part of a real tuplet or more conveniently the imaginary part of complex number, why can't you? But again, that is a useful mathematical representation, not the science at hand - which is new.

Jun 28, 2019
And Lagrangian cycles still describe the discrete features needed to represent any particular phase.... yeah, new!

(I take it "Lagrangian cycles" refers to the orbifolds that makes sense.)
I'm taking it that SOE is a recombinatory bot that takes in physics, math, and philosophy jargon and spits out plausible-sounding "Mark V. Shaney"-style gibberish.
"When I meet with people on a professional basis, I want them to shave their arms" (famous Markov-chain based bot example, Scientific American, 1989)

Jun 28, 2019
And Lagrangian cycles still describe the discrete features needed to represent any particular phase.... yeah, new!
Still, only a formal transform is needed to illustrate the homology; as Sokal put it:

"In quantum gravity, we may expect that a similar representation will hold, except that the two-dimensional manifold with boundary will be replaced by a multidimensional one. Unfortunately, multidimensionality goes against the grain of conventional linear mathematical thought, and despite a recent broadening of attitudes (notably associated with the study of multidimensional nonlinear phenomena in chaos theory), the theory of multidimensional manifolds with boundary remains somewhat underdeveloped."
--Toward a Transformative Hermeneutic of Quantum Gravity. Alan D. Sokal, Nov. 1994

Jun 28, 2019
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.


All very good and well done. However, these little techniques of theirs using laser beams are a contrived and artificial use of those beams - and are unlikely found in Nature. They could possibly find even more ways to twist and turn the lights into many other configurations - but it is still only manmade and artificial. It is more ART than Physics, or perhaps a little of both.

Jun 29, 2019
Wonder how this 'new' property can be utilized for propulsion, especially space propulsion.

Jun 29, 2019
Actually SEU, Lasers and masers are found in nature (certain frequencies in the solar output, for example), we just found a way to replicate them after we found super-bright, coherent light sources, and had to figure out how and why they happened, now a century on we take it all for granted. It turns out that there are several different ways to create the lasing effect.

It seems that if we can create the conditions in a lab, then it is entirely possible that the conditions would be possible to come into some workable configuration in a random way, given enough time. Many things we do in the lab are trying to re-create what has been observed 'in the wild', Lasers and their precursor, Masers, come from trying to replicate things they had already observed. While possibly unlikely, the idea of crystal whiffs of vapor in a vacuum held by light waves in nature is still entirely possible but would be extremely difficult to study in situ.

Thus lab is much easier.

Jun 30, 2019
Is it me or the picture of the crescent half donut looks a lot like a recent black hole photo.

Jun 30, 2019
Is it me or the picture of the crescent half donut looks a lot like a recent black hole photo.


You are correct. It does resemble quite a bit the donut photo of Messier 87's Black Hole.

Jun 30, 2019
@Steelwolf
I was going to go along with your saying that lasers and masers both occur in Nature, had it not been for the Wiki article that I read just awhile ago about "LASER".
I could not find anything anywhere in the Wiki article to indicate that both or either Lasers and Masers occur outside of the lab of the early 1900s. But every scientist mentioned in the article said basically the same thing, "STIMULATED EMISSIONS" regarding the Laser light emissions from, and caused by a DEVICE.

Jun 30, 2019
From Wiki:
Foundations
In 1917, Albert Einstein established the theoretical foundations for the laser and the maser in the paper Zur Quantentheorie der Strahlung (On the Quantum Theory of Radiation) via a re-derivation of Max Planck's law of radiation, conceptually based upon probability coefficients (Einstein coefficients) for the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation.[17] In 1928, Rudolf W. Ladenburg confirmed the existence of the phenomena of stimulated emission and negative absorption.[18] In 1939, Valentin A. Fabrikant predicted the use of stimulated emission to amplify "short" waves.[19] In 1947, Willis E. Lamb and R.C. Retherford found apparent stimulated emission in hydrogen spectra and effected the first demonstration of stimulated emission.[18] In 1950, Alfred Kastler (Nobel Prize for Physics 1966) proposed the method of optical pumping, experimentally confirmed, two years later, by Brossel, Kastler, and Winter.[20]


Jun 30, 2019
@Steelwolf
Perhaps I may have misread the Wiki article on lasers and masers. If so, please show the paragraph(s) where I was mistaken and that Lasers and Masers do occur outside of the Lab, in the Cosmos.. Thanks

Jun 30, 2019
Correction to this text. This is not the discovery of a new property of light. This is a discovery of how to bend light into an angular momentum. Fluids have angular momentum and they are simply denser than purer light particles. All matter is light. I think that makes this less complicated to relate to. There should be many ways to achieve that distortion.

Jun 30, 2019
@SEU:
@Steelwolf
Perhaps I may have misread the Wiki article on lasers and masers. If so, please show the paragraph(s) where I was mistaken and that Lasers and Masers do occur outside of the Lab, in the Cosmos.. Thanks

You always misread everything. Just accept it and live with it.
Laser: https://en.wikipe.../MWC_349
Maser: https://en.wikipe...al_maser

Jul 01, 2019
Perhaps this will allow entangled photons to violate the supposed "no Communication Theorem" (a tautology which was really baked into quantum theory when they invented it). As such it might explain the Fermi paradox. They're out there talking we're just not listening.

Jul 01, 2019
No it won't because it wasn't "baked into quantum theory when they invented it".

Jul 01, 2019
"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. "
- sounds EXACTLY what an 'ELECTRIC UNIVERSE' would predict of them - funny how this physics is gradually going there, little step by little step - more shapes & properties tying into this... all those twisted vortices showing helixes & doughnut shapes........are you guys still not getting it - all the properties of the Plasma Universe ? Well, this comment may get killed as some of mine do, but I often come in here to try & wake you all up.

Jul 01, 2019
I'm very happy to see that my ideas are appreciated. I don't understand why you don't contact me, we could work together. I have many discoveries in all areas. I published the same thing on the livenewworld.com site before you. Contact me on the site address reviweslnw@yahoo.com

Jul 01, 2019
.... spherical harmonics .... single photon. .

Hermite photon... O(N) or U(1) on the fall my friend? Energetic dense projected. A lack of a photon is a photon, so long as we condition on a bosonic background.
I can represent phase by taking the second part of a real tuplet or more conveniently the imaginary part of complex number, why can't you?

Because you take the prior of transaction, to constrain the serendipitous. Are partitions a free action? We don't know that the drunk gets home in three, yet as you chase the Zig-Zag you suppose only bound rabbits are not sour. Atop compact the world must get smaller, eh?
And to DanR. I am but a meat robot. Alan D. Sokal wasn't wrong or right. The ontic duality can buy one in the same with a scarred drum, yet spactime operators seem to condition without the constraints or orient when it comes to defects.
What will it be Wernicke on potential anticipation or Broca's on look up? How about soft and hard on bootstrap.

Jul 01, 2019
Looks like it's a non-linear optical property of argon, not a property of light per se. Another example: nobody says parametric down-conversion is a property of light.

Jul 01, 2019
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Jul 02, 2019
The property of spin induced by the interaction of opposite charges of equal mass was originally discovered as a finding of the LANL Plasma Research Program. It was announced at the 1989 LANL International Atomic Physics Summer School.

Jul 02, 2019
interesting
tho ufos can do more with light beams like bending, curving etc

Jul 03, 2019
@SEU, Ojorf already pointed to some basic relevant places to look. Even our own sun puts out some laser radiation, just a fact of how the mechanism works. The wiki-link Ojorf posted shows Jupiter lit up with synchrotron maser emission in the polar aurorae.

It really is a basic and not-uncommon light form in the universe at large. That is how us lowly humans are able to play with it: it happens fairly easily with certain materials and energy regimes, not needing extremes.

Jul 04, 2019
Just to reinforce @Ojorf's point, here is the paper on lasers and masers around MWC349A that is the source of the Wikipedia article linked: https://arxiv.org...2953.pdf

Open access, as always on arXiv.

Jul 14, 2019
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