The animations are pretty, but the article is short on actual explanations. How does adding a detector to one of the slits kill the interference pattern? How exactly do the particles interact in the configuration space? How does entanglement arise in this picture? Hopefully these issues are addressed in the actual paper, though it's not at all obvious from the abstract.
Presumably, if you put a detector in front of one of those slits, the particles cannot pass through both slits, and thus you wouldn't have those two moving collections of particles. You would have one moving collection, which would simply fan out without interference.
Right. But I think the idea is there are two groups of particles when both slits are open. When one is blocked a particle detector, they can't go through both slits.
With a detector in one of the slits, you will only see one group, not the unmeasured state with both groups.
That's not how the double-slit experiment works. Both slits remain open at all times. The detector only detects the passage of the particle through one of the slits.
This is the first explanation of a 'many worlds' theory of quantum mechanics that has ever made sense to me. The animations are excellent:
http://www.preposterousuniverse.com/blog/2014/12/16/guest-post-chip-sebens-on-the-many-interacting-worlds-approach-to-quantum-mechanics/