In the recent Australian National University experiment by Dr. Truscott, Wheeler's Delayed Choice thought experiment was carried out with ultra-cooled helium atoms. The Nature Physics publication is below, with other explanations available online. What I'm interested in is a plausible explanation that occurred to me.

So, the state of the atom is indeterminate between the first light grating and the second possible light grating. This second event, only determined to actually happen (or not) after the first event occurs, seems to influence the behavior (either particle or wave behavior) of the atom between the first and second grating. There are two plausible explanations. Either the atom doesn't actually exist as a wave or particle between these two events, and this behavior is only determined at measurement, or (obviously controversially) the future event effects the past.

I'm interested in this second explanation, because in my mind it resembles the local-realism violations of certain entangled pairs. There is support to the idea that a particle can be entangled with itself (though the usefulness of this until now was moot), so my question, as stated above, is this: could this single helium atom be entangled with itself between the first and second gratings? As a measurement of one entangled particle causes the other to take on the measured state, this behavior seems at the very least parallel. When this atom is measured at the second grating (let's call this t=1), not only is the behavior determined for that point, but as that collapses the superposition of having traveled as either a wave or particle, it also collapses it at its state immediately after the first grating (for now, t=0).

This does require the atom as it exists at t=0 and at t=1 to be considered an entangled pair to have a consistent explanation, hence the question.

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3343.html