Your question is basically what the entire article is about. Short answer: difficult when dealing with a system that by design is not supposed to read any part

Your question is basically what the entire article is about. Short answer: difficult when dealing with a system that by design is not supposed to read any part of the data. "The current generation of quantum cryptography systems are point-to-point connections over a single length of fibre, So they can send secure messages from A to B but cannot route this information onwards to C, D, E or F. That’s because the act of routing a message means reading the part of it that indicates where it has to be routed. And this inevitably changes it, at least with conventional routers. This makes a quantum internet impossible with today’s technology" Impossible with today's technology = extremely difficult. Routers have to read the data in order to know where it is supposed to be routed to. Quantum routing isn't allowed to do that. That's a difficult problem. edit: apologies for duplicating previous answers, should've refreshed the comments page before posting.