I'm returning to the old thought experiemnt of a controlled electron beam pointing at one or two slits. By controlled I mean that the electrons are released with sufficient time between firings that no two subsequent electrons should interact.
I found the this paper (https://iopscience.iop.org/article/10.1088/1367-2630/15/3/033018) where they perform exactly this experiment - but the results surprised me and I wondered if anyone could help me clarify.
When both slits are un-masked we see the good ol' inteference pattern - a big sinc for the single slit modulated by narrow fringes from the interaction. But in the edge cases, where only one slit is unmasked, I'm surprised that we still seem to see narrow fringes (maybe clearest in the penultimate couple of panels).
How are these occuring?