I'm a bit confused about quantum entanglement. First of all, how exactly do you entangle two atoms? I've heard about how they entangled atoms in quantum teleportation experiments, but I don't get how they did it. I've heard that the atoms must "interact", but what exactly does that mean? Do they have to touch? Do they have to be within a certain distance - like a foot or an inch - from each other? Also, can atoms be entangled if they're really far away? Like if one was in New York and the other was in LA, could you entangle them? Or would you have to, for example, entangle them both in LA and then take one to New York?