Building a quantum internet is not as simple as just connecting two quantum computers.
Imagine for a second a quantum key distribution (QKD) system based on photons: one of the nodes sends a quantum state encoded in a photon, and the other, after some time, receives it and measures it in any of the basis. However, due to decoherence of the qubits, the state that was sent initially might not be the same as the one that's received, affecting the communication and performance of the protocol. It has been tested and simulated that for a QKD system, more than 100km is fatal for the communication rate. How can we circumvent these issues? Especially if we want to move further to more complicated protocols?
In the video, the basic blocks needed for a quantum network are explained, with emphasis on the communication channels, quantum repeaters, and introducing the concept of entanglement distillation.
Suppose we are just sending photons (light) using optical fibers, just the same way we do so for classical internet. Why can't why use the same repeaters as well?