This novel radio technique allows the implementation of, in principle, an infinite number of channels
How does that work? Photons have spin 1. There's only three possible angular momenta a photon can have.
Also, what kind of equipment would be necessary to use that? I doubt it would be worth while.
There's only three possible angular momenta a photon can have.
First, two and not three, the spin projection 0 disappears for massless fields. Second, those are basis states, any normalized linear combination is also allowed. Third, they are talking about orbital angular momentum, not spin (I am unsure about the details, though).
Also, what kind of equipment would be necessary to use that?
They show their helix-shaped satellite dish, doesn't seem overly high-tech.
Encoding many channels on the same frequency through radio vorticity: first experimental test
"We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques. This paves the way for innovative techniques in radio science and entirely new paradigms in radio communication protocols that might offer a solution to the problem of radio-band congestion."
"Moreover, our experimental findings demonstrate that the spatial phase signature was preserved even in the far-field region and for incoherent non-monochromatic wave beams. These results open up new perspectives not only for wireless communication but also for physics and astronomy, including the possible detection of Kerr black holes in the test general relativity"
This looks too good to be true, but I cannot see any obvious issues, and they have an experimental confirmation.
If this pans out, it would be a black swan in the making for many of the wireless spectrum allocation/licensing authorities and companies.