[LINK] An amazing breakthrough in wireless communication, or a pipe dream?

Channels distinguished by vorticity experience crosstalk in the presence of plane scatterers like buildings, the ground, the sky... It seems pretty well restricted to what they used - a parabolic mirror, aiming it along a direct line of sight to the receiver.

This could potentially be very useful for communications in space, where we can't spatially resolve a large number of faraway receivers. You can address by vorticity instead of frequency, and each receiver gets a full spectrum of bandwidth.

I could be off on this, but in short, it looks legit, if specialized.

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This doesn't technically increase the number of channels available. What it does make possible is distinguishing these channels without having to have lots of antennas cooperating on sending every signal. One antenna, one channel.

Italian nationalism in the sciences fascinates me.

The final results of this experiment were publicly demonstrated on 24 June 2011 on Piazza San Marco, Venice, in the presence of the international press, experts, well-known personalities and the general public. In the style of Guglielmo Marconi, we realized this first public demonstration of radio vortices by also involving ordinary people in the experiment—a different way to communicate science. A light and sound show with projections onto the fa¸cade of Palazzo Ducale explained to the audience what the experimenters were doing. More than 2000 people attended the ‘live’ experiment at 21:30 local time and when the signal was tuned from vorticity zero to vorticity one at the same frequency and transmitting simultaneously, a rifle shot was heard, in honour of the first radio transmission made by Guglielmo Marconi in 1895. After this, on the facade of Palazzo Ducale the words ‘segnale ricevuto’, which in Italian means ‘signal received’, were projected.

Neither; just a subset of existing MIMO technology.. And MIMO is already part of standards like 802.11n.

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.

Oh, this is a good idea. Yeah, totally possible. The only issue is that now you need two antennas to receive the signal, and you need to have electronics good enough to get at the phase information. The backwards-incompatibility might be a problem, and I don't know whether the electronics requirements are already easy to satisfy or not.

If this works, could it also be applied to fiber optics?

I don't quite grok rotational effects in EM waves, perhaps someone can enlighten me: doesn't circular/elliptical polarization allow the same kind of effect? (I.e., a theoretically infinite number of overlapping but separable signals.) Or is circular polarization fixed to a single rotation per wavelength?