Awesome Homemade Quantum Eraser experiment
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it as a do-it-yourself example of a quantum eraser setup, both to show how to try it at home and as the starting point for questions about what the result really proves.
Recommended by 2 people across 2 different months, 2013 to 2023.
What it is
A homemade demonstration of the quantum eraser effect using a laser pointer, a double slit, and polarizing filters taken from 3D glasses. Orthogonal polarizers on the two slits remove the interference pattern, and a third filter at 45 degrees brings it back. The uploader also argues in the description that the effect is genuinely quantum rather than just classical wave behavior.
What people said
Recommends N. Virgo · 2013-05 · Physics Stack Exchange · on “Quantum mechanics and everyday nature”
This video [this video] and this article [LINK] both show you how to make a quantum eraser experiment [LINK] at home using only a laser pointer and some polarising filters, which in the video are obtained from 3D glasses*. One could argue that this doesn't really count, since if you really think about it, you should expect the same result if light were just a wave. However, if you accept that light is photons then it very nicely demonstrates that the interference pattern disappears if there's a way to know which path the photon took, which is a very distinctly quantum phenomenon. (*) In my experience, most 3D glasses tend to have circular polarising filters rather than linear ones. This doesn't s
Recommends user21420 · 2014-06 · Physics Stack Exchange · on “How is a photon/particle measured when passing through one of the slits of the Double Slit Experiment?”
Information about Double Slit Experiment: In double slit experiment, light behaves like a wave when it's not observed (in simple words you don't know in which slit photon passed through), because it's a wave, when two waves meet each other they will interferece [LINK] and on detector screen you will see interference pattern like this: But if you will put detectors on the slits, you will observe in which slit each photon passed though, and because of that interference pattern will disappear, because by observing light, it no longer behaves like a wave (in other words it's wavefunction has collapsed) instead it behaves like a particle (Photon) so, on a detector screen you will no longer see in
Cites Craig Gidney · 2016-06 · Physics Stack Exchange · on “Double slit experiment; evidence of wavefunction collapse”
Note that your first video is showing a simulation of the experiment [LINK] . From the transcript: We don't have the equipment to do it for you, but we can show you a simulation of what you would see. Right now, you are watching an animation showing what we would expect to see if we could do the double slit experiment with only a small number of photons in a system at a time. Also note that "detectors prevent interference" is a prediction of quantum mechanics. It's not exclusive to collapse interpretations. With those noted... A paper that does an actual experiment and records the results is 'Controlled double-slit electron diffraction' by Roger Bach et al from 2013 [LINK] . They use a block
Cites Anthill · 2020-05 · Physics Stack Exchange · on “Delayed choice quantum eraser experiment involving light and polarization filters”
I read a post [LINK] about trying Young's double slit experiment at home, and the first comment suggested a DIY delayed choice quantum eraser experiment [this video] . In the video, they use two polarization filters on the slits, one at $0^{\circ}$ and one at $90^{\circ}$ , to trace the path of the light and thus stop the light from interfering, and then a $45^{\circ}$ angle one to erase the information and obtain the interference pattern again. I have a few questions about this: Isn't the reason for the light not interfering in the first part of the experiment the fact that the two polarization filters set the light in orthonormal states that don't interact? I imagine that if after we polarize t
Cites Cloudyman · 2021-12 · Physics Stack Exchange · on “Has a double-slit experiment with detectors at each slit actually been done?”
My understanding of the famous double-slit experiment is that, when both slits are open, a wave-pattern interference arising from the two slits is observed. This is a different pattern than summing the pattern from each slit individually. This is not unusual as the same thing happens with water and sound waves, for example. The odd/novel things (with regards to classical physics) are: the interference pattern is observed even if you only send one photon or electron etc through at a time (i.e. it appears the particle 'interferes with itself'). And If you detect which slit the photon or electron etc goes through, there is no more interference pattern - you observe the sum of the individual sli
Cites Cloudyman · 2021-12 · Physics Stack Exchange · on “What is the predicted outcome of this quantum eraser experiment?”
This [this video] demonstrates a doable-at-home quantum eraser experiment. To summarize in brief, a laser is shined through a double-slit, causing an interference pattern on a white poster 3 meters away. When a horizontal polarizing filter is added on the left slit and a vertical polarizing filter is added on the right slit, the interference pattern disappears. When a 45-degree polarizing filter is re-added after the slit, the interference pattern reappears. This is said to prove that knowledge of which slit the photon goes through eliminates the interference pattern. Because with the polarized light we can tell which slit it went through, there is no interference pattern. Because with the 45-deg
Cites likeabbas · 2023-01 · Physics Stack Exchange · on “Video of Double Slit Experiment Observer Effect”
This was the only video I could find demonstrating the collapse of the wave function using photons (a laser in this case) [this video] . She uses polarization filters to define which slit the photons came out of.