For convenience, I gathered a few comments of mine into a blog post.
despite phase shifts being the main cause of the described effects.
what are the other ones?
(when i’m thinking about splitter with pi/2 phase shift, i’m thinking about coupled line coupler or its waveguide analogue, but i come from microwave land on this one. maybe this works in fibers?)
what are the other ones?
I guess the rest of the experimental setup that recombines the photon amplitiudes. Like if you put 5 extra beam splitters in the bottom path, there wouldn’t be full destructive interference.
when i’m thinking about splitter with pi/4 phase shift, i’m thinking about coupled line coupler or its waveguide analogue, but i come from microwave land on this one. maybe this works in fibers?
I’m not sure how you’d actually build a symmetric beam splitter: wikipedia said you’d need to induce a particular extra phase shift on both transmission and reflection. (I’m fully theoretical physics so I’m not too familiar).
pi/2, sorry
In microwave land we have something called rat race coupler which can be used as an in-phase 1:1 splitter. This thing can be manufactured in waveguides so maybe (narrowband) fiber optic implementation is possible
https://www.microwaves101.com/encyclopedias/rat-race-couplers
