Saturday, January 25, 2020

double slit experiment - Are photons blinking?



Is a photon passing through a point in space blinking relative to that point?


If the photon for some reason destructively interfere with it self at that point, what happen to it? is it off or is it somewhere else?


By blinking I mean toggling between visible and invisible / detectable and not detectable or maybe fade in / fade out when considering its wave nature.



Edit When the wave goes to zero every half wavelength is it possible that the photon disappears every half wavelength? is it disappearing in way similar to what it does after a destructive interference with another photon only that it will come back completing the wavelength?


Edit
In other words, does the fact that a photon as a particle disappears when the photon as a wave destructively interfere with another, means that the photon as a paricle also disappears at the point in space-time where its wave functon is zero between a crest and a trough? From Anna's answer and comments the photon is not regarded as a wave in its own but i dont understand this.



Answer



The photon is an elementary particle in the standard model of particle physics.


The theory at present has elementary particles as point particles in a quantum mechanical theoretical model using quantum field theory. This leads to the Feynman diagram representation of elementary particle interactions which leads to calculating measurable quantities, as crossections and decays.


The point nature of the particles appears when they are detected, and detection means interaction with other particles or fields. See this singe photon at a time experiment, the photons detected by the point seen on the screen on the left.


singlephot



single-photon camera recording of photons from a double slit illuminated by very weak laser light. Left to right: single frame, superposition of 200, 1’000, and 500’000 frames




As you see on the left, there are dots, not spread out energy. The wave nature of the photon is in its probability amplitude as expressed by the modulus of its wavefunction, in simple quantum terms. The wave nature can be seen only by an accumulation of photons, which build up the same frequency classical light as seen on the far right.


You ask:



is a photon passing through a point in space blinking relative to that point?



as the first frames on the left show, the answer is no, it acts as a point particle when it interacts.



If the photon for some reason destructively interfere with it self at that point, what happen to it? is it off or is it somewhere else?




Point particles cannot destructively interfere with themselves in the theoretical model of mainstream physics. They leave a footprint consistent with the probability amplitude that describes them mathematically


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