Quantum technologies and information transfer. How it works?

Question

Physics

Hello!
How many times have I come across articles about quantum networks with speeds of 300-400 Gbps. At the same time, I know that it seems like the fastest quantum networks using a beam of light, when using quantum cryptography, they give out a speed of a maximum of a couple of Mbit / s due to the fact that the number of protons transmitted in one package tends to one in order to deprive an attacker of the opportunity to steal part of this package.
Also, some sources talk about the possibility of data transmission using entangled particles, other sources, on the contrary, say that this is impossible and entanglement will collapse after that.
So all the same, what kind of magic are these networks with great speed and complete protection? With what they are in general and with the help of what to do?

Answer 1

the speeds in quantum transmission systems are very small, barely enough to transmit the encryption key. After the key is transmitted, the information is transmitted in the usual way.