Where are the images of non-interference patterns?

Question

In the double-slit experiments, when photons are observed and therefore behave like particles, why don’t we see clear images of the photons casting the two straight bands with no wave interference patterns?

It seems like all the images shown online, in magazines or papers, only proves wave-like interference pattern confirming photons as wave, i couldn't find any images showing light behaving as particle, aka, forming no interference. Is there a reason for this?

Answer 1

The image you show is misleading or rather wrong, even. In the case where it is detected wether a photon goes left or right (usually done by putting a vertical polarizer in front of one slit and a horizontal polarizer in front of the other), the pattern at the wall behind does not indicate particles. The pattern will consist of two overlapping single slit interference patterns. These are usually much wider than the distance between the two slots, so it will appear as if there was just one single slit pattern. Here is a video showing the pattern (in this experiment, there are polarizers in front of the slits and then there is a third, movable polarizer which can "repair" the double slit pattern by forcing parallel polarization - you can see the single slit pattern when there are no fringes visible or when the third polarizer is not present).

Interference experiments with normal laser light are usually not a good way to demonstrate particle properties of light, since most - if not all - the phenomena visible in such experiments are fully explainable in the wave model of light. To exhibit true quantum mechanical phenomena, one would need a very low intensity light source that is able to deposit an energy of no more than about $10^{-26} \mathrm J$ of energy into our slits, because that energy corresponds to about 20000 photons of red light, not too many to distinguish them on the screen. Particle properties would then be visible on the detector screen: The pattern is not visible at first, only single points where photons were measured. After enough photons have been observed, the pattern will emerge in a granular way like here, though this is a pattern of electrons, but the idea is the same:

If the experiment were done with the polarizers, the single slit pattern would emerge in the same granular way.

Answer 2

When information is copied out of a quantum system interference is suppressed, an effect called decoherence. There is a large literature on theory and experimental testing of decoherence, for a review see

https://arxiv.org/abs/1911.06282

Measurements of photons are often destructive, e.g. - absorption by a detector. Non-destructive measurements in single photon interference experiments have been simulated:

https://arxiv.org/abs/1606.09442

Answer 3

Phenomena for photons

1. photons that are detected are absorbed and no longer reach the observation screen. Detectors can therefore not be used for the “which path” investigation.
2. even behind a single slit, the typical intensity distribution arises from areas with many and with few incident photons. It therefore makes sense to investigate this fundamental phenomenon first.
3. photons of visible light do not interact. The intensity distribution is therefore not based on interference between photons.
4. the deflection of each individual photon is also not due to self-interference on both sides of a single slit. To see this, it is sufficient to remove one edge. The deflection at the single slit still occurs.
5. since the interaction of the surface electrons of the obstacle with the photon has not been a subject of consideration so far (Huygens and Newton could not know anything about it anyway), a phononic excitation of the obstacle has not been considered so far. This in turn can be responsible for diffraction towards periodically changing intensity ranges.