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New Way of Observing Light May Boost Info Content
md_seymour observes: "Today's Astronomy Picture of the Day from NASA has a description and image of light that can twist as well as spin, based on research from Miles Padgett and Johannes Courtial of the University of Glasgow. They and their colleagues have apparently been able to sort individual photons by their orbital angular momentum. Since this characteristic of the photon is able to take on an infinite number of values, it may be possible to pack much more information into a light beam."
STAR FIBER!
Star Fiber Router could be called the "X-wing"
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... cross-coordinates ... any, and all, with the digits "8008" in them, in that string ...
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746f72706f72 as well ...
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
Worst. President. Ever.
For practical use, we need to not only be able to generate photons with a desired spin. As it is, this is still useful for cryptography, but if we want to start packing each photon (on a fibre-optic line or something) with a base 64 value instead of a base 2 value (for example) we need to be able to reliably generate the photon with the correct spin out of the 64. But once that goes say hello to cheaper internet speeds :)
Measuring the orbital angular momentum of single photons is a "brilliant" achievement, says Keith Burnett of the University of Oxford.
:)
Not that I understand one bit of what they're talking about, though
"Total destruction the only solution" - Bob Marley
Since this characteristic of the photon is able to take on an infinite number of values,
Not really though, right? Such values are discretized in the sense that the Planck length discretizes distance, right?
This is just circularly-polarized light, isn't it? Shine a laser through a polarizer and a quarter-wave plate, and that's what you get.
All it takes is nukes and nerves.
No, they're different.
Take a beam of circularly-polarized light (without orbital-angular-momentum), freeze time in your imagination, and look at the E-field vectors along the beam. The E-field vectors all point in the same direction. Over time they rotate around the beam axis -- that's what circular polarization means -- but the E-field-vectors are always aligned along the entire length of the beam.
Now instead imagine a beam of light with orbital-angular-momentum, and again freeze the beam in your imagination. Now the E-field vectors make a helix along the beam.
You get circularly polarized light by passing a beam through a polarizer and quarter-wave plate. You get light with orbital angular momentum by spinning the light source around the beam axis.
There's a short article about this property of light in this month's edition of Scientific American. Apparently this propery isn't new but rather largely ignored.
Well, there's spam egg sausage and spam, that's not got much spam in it.
Not a circle, like a 'corkscrew.'
I want technology based on this stuff yesterday. Also, get SETI looking for these types of signals.
Wow. First, let's assume linear polarization. The polarization angle could vary between 0 and 179.999 degrees. If the "twist" of the light could be considered as an "amplitude," then we could do a variant of QAM on a single photon. Depending upon how sensitive the receiving equipment is, and how precise the transmitting equipment is, it should be possible (in theory) to then encode at least 4 bits in one single photon.
Of course, building such a transmitter/receiver would be an engineering nightmare. But we can dream...
"-1 Troll" is the apparently the same as "-1 I disagree with you."
Scientific American has this article as well. I admit, i'm still scratching my head over it after reading it when i got the paper version last month...
Is orbital angular momentum (OAM) a bit of energy added to the photon, or is it just a redistribution of the "normal" energy of the photon? If it is a redistribution then does a photon with OAM have a different wavelength than a photon with the same energy but no OAM?
Does generating a photon with OAM transfer angular momentum from the generator to the photon? That is does emitting an OAM beam cause the source to spin?
Many questions that boggle my mind.
Stonewolf
As Far as i can tell, this means you could actually build a laser cannon that upends targets? Cool. In a gravitational field, that could hurt seriously at lower intensities than the usual "vaporisation" idea of lasers, right?