Thursday, 19 March 2020

quantum mechanics - Can an electron interact with itself to create interference?


I have been recently brushing up on my elementary physics concepts, specifically quantum physics. If I set up a single photon emitter and conducted the double slit experiment, it is possible for me to see interference. When I thought about this I realized that a photon is mass-less and travels at the speed of light, so time does not affect a photon. Therefore, a photon can interact with another instance of itself (which in our frame of reference exists in another time).



My question is, is this same effect observable when a single electron is fired at speeds much lower than the speed of light?



If so, how? For this to happen, the electron (which has mass and experiences time the way we do) has to be physically present at two locations at the same time (in both slits).



Answer




Yes, electrons can be brought to interfere with themselves. This can actually be shown in a double slit experiment, just as with photons.


The electron you are thinking of is a localized particle in space. Instead, you have to consider the electron's position as a wave function. The wave function can be non-zero at both slits and interfere with itself afterward. With electrons, you will also find the typical stripes (or rings, if you use a circular aperture as a single slit) that you found with photons.


This is one of the groundbreaking experiments that one can conduct in schools to prove that electrons actually are both, a wave and a particle.


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