In the double slot experiment I am aware of the photon source was composed of a material which released photons at a known rate.
The concentration of the photon source material was such that the probability of the release of a measurable quantity of simultaneous photons was next to impossible.
It does not matter if we can detect individual photons as long as there are not two photons released at once.
Due to the low rate of photon release the film was left to be exposed over several months.

The only benefit of detecting individual electrons would be in determining what property of the electron entering the slot causes the variation in placement after passing through the slots.

Duane Eddy

• Double slit experiments with single photons - harvey1 - October 26, 2003 - 23:27 UTC
  • The experiment has been done - yanniru - October 27, 2003 - 12:23 UTC
    • I found examples - harvey1 - October 27, 2003 - 15:27 UTC
      • Can you give a reference? - duordi - October 28, 2003 - 04:34 UTC
        • You know - harvey1 - October 28, 2003 - 15:17 UTC