In this experiment, they didn’t even bother measuring which slit each photon passes through. The 3D glasses don’t measure or observe the photons, they merely polarize them (although they do block 50% of light). The detector D_S doesn’t measure which-path information either. The researchers could have placed a circular polarizer in front of D_S, and when they get a hit they could have said with confidence “this photon came through the top slit!” but they didn’t even bother doing it this time. The fact that the 3D glasses alter the light in a manner which makes the which-path information theoretically measurable (even if not actually measured), alone is sufficient to destroy the interference pattern.
Comment on The real double-slit quantum eraser they don't want you to know about!
TWeaK@lemm.ee 1 year ago
So it turns out the original meme was kind of right? It just didn’t illustrate what it was talking about very well. According to @ada@ada@lemmy.blahaj.zone:
The double slit experiment is about observation.
When you fire photons through the double slits, one photon at a time, they cause wave interference patterns with themselves as if each photon travelled through both slits.
Yet if you set something up to measure which slit each photon passed through, they no longer interfere with themselves, and give you the two straight lines pattern, rather than the interference pattern.
TauZero@mander.xyz 1 year ago
NattyNatty2x4@beehaw.org 1 year ago
The original meme is definitely correct, idk why so many people were having conniption fits over it. In the double slit experiment’s simplest form, not measuring the photons leads to the wave interaction pattern and measuring the photons leads to the two bars as you’d expect from particles.
TWeaK@lemm.ee 1 year ago
It’s because it isn’t clear from the meme that the monkey is looking specifically at the interaction at the slits.
NattyNatty2x4@beehaw.org 1 year ago
It’s a preeeeeetty clear joke reference to the use of “observe” for the behavior changing if the photons are measured/interacted with
TWeaK@lemm.ee 1 year ago
It’s clear he’s observing something, but all too easy for the viewer to think the monkey is merely observing the pattern on the screen at the end. It also doesn’t help that there are a bunch of slight variations on the double slit experiment, like those listed in this post.
If the monkey was at 90 degrees to the experiment, looking at the slits only side on, then it might be clearer - though I’m not sure how you could draw that lol.