"two photons come out" part makes no sense though. On a target side, there's always single hit after single photon/electron, but distribution of theses hits as if said electron got through both slits and interfered with itself
P.S. the funny thing is - this works on any small thingy, measured up to 2000 atoms-big, as if it's the property of the universe itself
They did it by splitting a beam of particles into a pair of entangled particles and then setting up a way to measure the polarity of one of them after the point in time where it even hits the final screen. If you measure the polarity then, after the other stream of particles from the beam had already had time to make the pattern, the pattern will be two clusters. If you don't, it goes back to an interference pattern.
That one really cemented the notion in my head that this is just how the Universe is and not some local weirdness with particles and measurements.
https://www.youtube.com/watch?v=RQv5CVELG3U
This is the video if you're interested. Again, I'm no physicist and don't know if explanations are legit or statistically correct. But that little || trick that all other popsci videos play on you, that's a true concern.
You can check it out here.
Summary https://www.stonybrook.edu/laser/_amarch/eraser/index.html
Paper https://www.stonybrook.edu/laser/_amarch/eraser/Walborn.pdf
My fascination with these experiments has never been due neat clusters of impacts, although popsci depictions have clearly tainted my memory.
https://iopscience.iop.org/article/10.1088/2058-7058/12/11/4
> The largest entities for which the double-slit experiment has been performed were molecules that each comprised 2000 atoms (whose total mass was 25,000 atomic mass units).[19]
The electron/proton entering a slit is affected by gravity!
Presumably a gravity based detector would have similar issues as these particles are affected by gravity (as can be seen around black holes)
https://www.nature.com/articles/s41567-019-0663-9
> Here, we report interference of a molecular library of functionalized oligoporphyrins with masses beyond 25,000 Da and consisting of up to 2,000 atoms, by far the heaviest objects shown to exhibit matter-wave interference to date.
It would be awkward to say that the 2000 atom molecule comes out of both sides... but it does, until you look.
The double slit experiment is not a duplication cheat of reality... it's weirder than that.
I thought the takeaway wasn’t that the particle comes out both sides, the implication is that the behavior of a single particle is the same as the behavior of multiple particles - that is to say, it appears to be an interference pattern, even when there should be no other particles to interferes with the single one.
This is fundamental to 100 years of quantum mechanics and underlies most of physics including all semiconductors, materials science, chemistry, lasers, etc. The double slit experiment is just a very good illustration of the principle boiled down to its essentials, which is why it's everywhere in pop-sci. It makes for more accessible story than describing how a hydrogen atom works.
There is no photon multiplication happening on the double slit.
It is as if every photon that went through the slit is somehow aware of all other photons that did so too so each photon can choose the (random) position where it hits on the wall behind the slit such that together they look like as if a WAWE went through the slit.
That is (one reason) why they call it "Quantum Weirdness". God is playing dice with us
Why isn't it just that there's a probability density function that describes the aggregate outcomes of a large number of samples from a random process? Why is "memory" involved?
There's no photon multiplication, and no "all other photons" changing their path.
There is some inter-photon interaction because they are bosons. But it's not significant enough to impact the multi-slit experiment. And the experiment works exactly the same way if you send only one photon at a time.
You still do not understand what is happening, please READ the article, it shows that the wave function doesn't go through anything and the it certainly doesn't create the interference pattern.
https://en.m.wikipedia.org/wiki/Perturbed_angular_correlatio...
I haven’t used it for my research, but it’s an incredible local probe of electric and magnetic fields in materials. There’s no other technique that I’m aware of that smuggles information about the chemical structure of a single coordination sphere into such clean, distinct emissions. The brief excited state of the isotope after the first emission event and before the second is sensitive to practically everything. It all shows up in the deconvoluted spectra.
Shame nearly all the isotopes that work for this are not ones that are super interesting for modern quantum materials. Perhaps that will change out of necessity.
In fact the photon may not actually exist. and I have questions as to what "single photon experiments" are actually measuring. let me explain.
The EM field is not quantized, or at least not quantized at the level of a photon, what we call a photon is the interaction of the EM field with matter, or more precisely with the electron shell of matter. it is the sound of the wave breaking on the shore, not the wave.
Now none of this actually matters as the only method we have of interacting with the EM field is through matter(electrons really) so we can only measure it in photon sized increments.
But, to "solve" the wave /particle conundrum, I like to think of it as fields all the way down. A "particle" is then a localized and quantisized interaction of said field with another field.
If you think of particles as small billiard balls flying through space on some ballistic trajectory, you'll soon run into all kinds of trouble and the mental model breaks down.
Or in insisting on referring to the electron as a particle.
“We begin by throwing an ultra-microscopic object — perhaps a photon, or an electron, or a neutrino”
However note that we can only perturb the em field in photon sized energy levels, and we can only pick up disturbances of the em field in photon sized bunches as well. Not sure what this implies for how em field energy is accumulated on electrons in order for us to detect it.
I don't agree with this. You can absolutely consider a classical (non-quantized) EM field interacting with quantized matter. This semi-classical model can describe the photoelectric effect, but it cannot describe other experimental observations such as sub-poissonian photo-detections / photon anti-bunching.
Only one photon comes out, but it can interfere with itself if it had the possibility of going through either slit.
That nuance aside, the Quantum Eraser Experiment is a real physical experiment that covers what I think you're asking about. If you send photons through double slits in a setup where you can tell which slit the photon went through, you don't get an interference pattern. If you can't tell, you do get the interference pattern.
Edit: Thank you all for the responses, it has been very educational. It appears I was misunderstanding the most important aspect of the double slit experiment. A photon is a wave function when unobserved, it literally goes through both slits and creates an interference pattern like how waves in water would. However, when observed at the slit, or at the detector screen, the wave function collapses and only one photon(billiard like particle) will be detected.