where is the question? i think you misunderstood the article.
the top-left and bottom-left pictures represent the same apparatus, as well as the top-right and bottom-right.
let's distinguish:
before detection, the electron is in a superposition, so its wave function is in different places simultaneously
after detection, the wave function collapses so we no longer have a superposition and the electron acts like a classical particle.
what i wanted to say in...
there is a long discussion in this forum about photon refraction and reflection
look at the thread "mach-zehnder interferometer experiment" or something like that
yes but again, maybe i can't figure out to which mirror the mometum went, but the electrons of the mirror know if their momentum is changed or not.
are the electrons of the mirror in a superposition too?
another question:
the wave function of the photon takes, in the same time, both paths, right?
let's consider path number 1: the photon (or its wave function) transfers, for example, 3/4 of its momentum to the mirror.
let's now consider path number 2: the photon transfers 3/4 of its momentum to...