Existing prototypes of quantum communication systems use the simplest, binary code. One photon is one bit, one or 0, which is very easy to implement. But this is a real waste, when it comes to advanced and knowledge-intensive systems. No, in one photon you can fit at least twice as much information and scientists from the University of Ottawa have proved that the principle of 4D quantum encryption works.
From 2D, the encoding in 4D is different in that a single photon is assigned a two-digit value. This can be 00, 01, 10, and 11 - the total is four different values. For transmission of information, the usual quantum states of a photon and the same equipment are used - the encryption algorithms simply change. In addition to a noticeable increase in the data transfer rate, this also promises an increase in noise immunity of communication lines.
But the theory is a theory, but what in practice? Canadian scientists climbed the roofs of two buildings at a distance of 300 m and placed laboratory equipment in wooden boxes for at least some protection from the weather. Below, the big city was buzzing, sparkling and radiating radio waves. The air, to put it mildly, was thoroughly clogged. And so, in such conditions, the 4D quantum encryption system managed to transmit information with a loss level of only 11%, much below the permissible maximum.
After processing the data, taking into account all the correction methods, the 4D system showed a throughput of 1.6 times higher than 2D. The next step will be to test the operation of systems with three transmitters over a distance of 5.6 km using adaptive optics. And then the equipment will be installed on a drone or a helicopter and will try to establish communication with the moving object. And then ... so far in the University of Ottawa does not think, although infinitely happy with the opening perspectives.