Has this type of experiment ever been performed? Firing electrons one at a time we can easily get the which-path information and see if interference dissapears or not. What actually happens? Also, if we do the double slit experiment with a usual laser but in a smoked enviroment (in order to see the tracks before and after the slits) what would then happen? But for this i actually got an idea. The tracks of the photons in the smoke are not equivalent to the tracks of the electrons in a bubble chamber because in the first case the photons are either absorbed or scattered by the atoms. So the photons that actually reach the wall after the slits havent interacted with the smoke ==> we will observe the interference pattern. Is the idea correct?