We know that single photon interference does occur, but does single photon diffraction also occur.
Yes I know, single photon will not produce an interference pattern, but when a lot of single photons are bombarded one by on the screen we start to see an interference pattern building up.
However, I have not seen any video or a paper showing that single photons also create a diffraction pattern when bombarded one by one on a screen, through a single slit.
I found at some other places that, single photons collectively do form a diffraction pattern. However, some books and explanations mention that single photons do not form a diffraction pattern.
I have got mixed answers to this question.
Can someone elaborate on this.
Well a photon is subject to these weird QM effects. The photon is subject to diffraction for my understanding, but the screen takes the measurement for which the superposition breaks down. Thus, it does but you will never measure it :D
What is it for?
Chetan, I think its fair to say, that any far field intensity pattern resulting from diffraction of a large flux of photons, will also be seen as a statistical distribution of 'landing site' of a single photon's passage through the same diffracting structure. Or in short, yes, a single photon should be subject to diffraction (in a quantum manner) by a single slit.
Yes, it should be just like how electrons (particle) produce diffraction pattern. However, books like Feynman Lectures and people who argue about observer effect using double slit experiment, show a Gaussian in their graphs, rather than a diffraction pattern, which is misleading.
This is the reason for confusion,
Check this,
https://i.stack.imgur.com/qoGu7.jpg
Although it looks like a Gaussian the way the figure is drawn, it is really showing (most of) the main lobe of a sinc squared function. It forms the envelope of the typical 'double slit' pattern. If more of the of the curve was shown, it would be seen to reach zero each side of the main lobe, then rise again to form a smaller side lobe further out, and so on. Hence, in the case of double slits, since the slit width is smaller than the spacing between slits, the width of the envelope lobes are large in comparison to the spacing of the peaks due to interference between the slits.
This description below from University of New South Wales should help.
http://www.animations.physics.unsw.edu.au/jw/light/single-slit-diffraction.html
First, diffraction and interference are not separate phenomena. Diffraction is wave-like mechanics, and interference is just one particular consequence of the diffraction model.
A single photon *does* interfere. In fact, you can say that photons only interfere with themselves. If we perform a double-slit experiment with a single photon, then in the observation plane its wavefunction will take the form of the familiar fringes. However, performing a measurement of the photon's position collapses the wavefunction into a single point. Hence an observation of an individual single-photon interference experiment does not produce the interference pattern.
However, if we perform this experiment repeatedly - even if we assured that only a single photon was present in the experiment at any given time - over multiple observations that detected positions will form the interference pattern.
Hallo,
Maybe this article will help you.
Article Observation of non-diffracting behavior at the single-photon level
@Mark Gardner Yes you are right, I got the point. It should be a (sinc)^2 function (to be precise) cut before other peaks show up. Books should mention it as this causes confusion.
The slit size is small for interference pattern, if it is larger, we will see a pattern which shows diffraction+interference, where the side lobes i.e. other orders are visible (like one shown down below)
Got your point, thanks.
@Tomas Santiago, can you elaborate on the paper.
https://en.wikipedia.org/wiki/Double-slit_experiment#/media/File:Single_slit_and_double_slit2.jpg
@Chetan
In my view it will be difficult to see the diffraction pattern from intensity point of view
Theoretically there will be diffraction .
B.Rath
To convince yourself that single photons do display the interference and diffraction phenomena, consider that the standard detectors used in nearly all XRD instruments are photon counters. The detect single photons, make an estimate of the the photon's energy, then count the ones in the energy range of interest.
You can check the following article for diffraction/interference of single photon..
http://www.optics.rochester.edu/workgroups/lukishova/QuantumOpticsLab/2013/OPT_253/Madhu_James_Lab02%20Report_Group%20B_James.pdf
A single photon would be diffracted after passing Young's double slit and interfere on a screen. This is because a single photon would act like wave (not a dot/particle, but wave) and diffract with itself. Since we cannot sense the result of a single photon, the experiments send many single photons one after another to observe the interference.
For more articles/papers you can visit the following link..
https://scholar.google.com.tr/scholar?q=single+photon+interference&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwi3gL_y5PnVAhXLuhoKHf4oCTcQgQMIJTAA
Start from this. Single atom ~ 1 Angstrem in size emits single photon ~530 nm.
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