Lately China is investing heavily on quantum communication technologies. And it is news of these days that Chinese scientists have been able to complete a "photon phone call" hacker-proof exploiting the so-called entanglement. Let's see in detail what they did and why.
The Beijing experiment aimed to transfer three identical photons from a satellite in orbit to three terrestrial stations distant 1200 km from each other. Obviously these photons have not transferred the greeting of the grandmother or other, but simply have shown that everything is possible.
The peculiarity of this experiment derives from the fact that, with the use of individual photons, the transmissions made with this system would be impossible to intercept. It should be pointed out, however, - and we tend to say it with some nationalistic pride - that the first terrestrial experiment of this kind was made by the Italian Paolo Villoresi of the University of Padua, while the one concluded a few days ago in Beijing became the first "space" experiment.
How does entanglement work?
THEentanglement is the phenomenon that two identical quantum particles retain the same properties regardless of the distance separating them. At first it was assumed that this phenomenon could also be the basis of studies on teleportation, but for now I would say that we are satisfied with the discoveries just made.
To understand how the "spatial" experiment of Beijing was realized, let's think that the satellite sends two identical photons: it is their identity to make them unique, and therefore in-hackable and inviolable. In fact, while our phone calls with your girlfriend or friends are made by innumerable photonic particles that could be "lost" or "intercepted", one unique password and based on a single quantum particle would be almost irrecoverable.
And that is why, in addition to China, they are also working on this project NASA,XNUMX-XNUMX business days and its European Space Agency and Canada. The steps taken so far, of course, are still preliminary and it would be foolish to imagine that one could start talking about a "quantum internet" in real time. In fact the difficulties they would already be evident in the eyes of the scientists promoters of these experiments: while in the space the photons can travel almost free from disturbances, once reaching the Earth's atmosphere the risk of "turbulence" and refraction is extremely high and therefore, at present, we must limit ourselves to imagine a future where a technological device can actually cancel the distances.
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