Charles Stross and Quantum Teleportation

[CJames]

I'm reading Singularity Sky and came across something that didn't sound right. Charles Stross is supposed to be known for accuracy in his sci-fi. But in this novel he claims quantum entanglement can be used for instantaneous communication. Here's the claim:

"A slower-than-light freighter had spent nearly a hundred years hauling the quantum black box at the core of the casual channel ... a twin to it had spent eighty years in the hold of a sister ship, en route to Earth. Now they provided an instantaneous communications channel from one planet to the other; instantaneous in terms of special relativity, but not capable of violating causality, and with a total capacity limited to the number of qubits they had been created with."

The only thing that makes me think he's not completely talking out his butt is the claim that it's not causality violating, but I'm not sure how that's possible. I would be disappointed to see psuedo-science in a Stross novel because I love his books, but that's what it looks like to me.

 

[DrClaude]

The only thing that makes me think he's not completely talking out his butt is the claim that it's not causality violating

That's a cop out. If FTL communication is possible, then causality has been violated. There is nothing one can do with one's quantum black box (qbb) that would tell them with is happening with the other qbb, therefore it cannot be used to communicate. A classical communication channel is always necessary to do something meaningful with the qbb.