The concept must at least exist, as Luke mentions it.
*THREEPIO Is there anything I might do to help? Luke glances at the battered robot. A bit of his anger drains and a tiny smile creeps across his face. LUKE Well, not unless you can alter time, speed up the harvest, or teleport me off this rock!*I’ve always taken that as proof that those things don’t exist in the SW galaxy. Luke said it jokingly, knowing it was impossible. The concept of those things exists, but in a sci-fi/fantasy way. That’s my reading/canon anyway.
Yes, but IIRC, Threepio’s answer in the novel implies the technology does exist, or at least the study of it…
http://starwars.wikia.com/wiki/Transatomic_physics