The recent post made me fear that a lot of you are taking this “monkey looks at double-slits” meme, which was only ever supposed to be a funny monkey meme, actually seriously. Honorable mention goes to @kromem, whose 12 posts on the topic, insisting that the quantum eraser experiment (but not the delayed-choice quantum...
The paper doesn’t use an actual screen, they only have the detector D_S that they move up and down to record the coincidences. I simulated what the monkey would see had there been a screen in place for the purpose of the meme. I copied down the datapoints from the graph and simulated 100,000 photons hitting the screen with the probabilities indicated by those points. My javascript pastie is available here: html.cafe/xcd2a5ed3?k=19f51bff26c65bcf253ee5257a5… Importantly, the monkey can never see images 4 and 5 on the physical screen - those can only be displayed on the computer. The monkey will only ever see image 3, which is the sum of 4 and 5.
Both this paper and the delayed choice quantum eraser experiment paper (arXiv:quant-ph/9903047) only show a single blob, not the double stripe. If anyone has a paper that clearly shows a photo with the double stripes the way it’s shown in the classic monkey meme, I’d like to add it to my collection!
Obviously if the slits are big and wide enough apart you will just get two spotlights, so that doesn’t count. It wouldn’t even demonstrate wave physics, let alone quantum. It has to be a paper where there is some switch you turn on or some filter you slide in place or whatever that makes the image on the physical screen toggle between two stripes and multiple.
If we cover one slit, it will look like figure 3, shifted to the side and at half intensity.
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.
The real double-slit quantum eraser they don't want you to know about! (mander.xyz)
The recent post made me fear that a lot of you are taking this “monkey looks at double-slits” meme, which was only ever supposed to be a funny monkey meme, actually seriously. Honorable mention goes to @kromem, whose 12 posts on the topic, insisting that the quantum eraser experiment (but not the delayed-choice quantum...