The wave of a photon/Measuring the particle

In principle in quantum mechanics is that when the path of the particle is known, there will no interference. This could be done by measuring the particles with detectors in the two paths. With photons that is quite difficult, because detecting always destroys the photon.

With particle detectors at the slits


The most simple and most often mentioned measuring is placing a detector before each slit.[1] However the experiment is probably not possible in this way, because photons cannot be detected without absorbing. There is also no publication where this experiment has been actually done.


  1. Feynman, Richard P. (1965). The Feynman Lectures on Physics, Vol. 3. US: Addison-Wesley. pp. 1.1–1.8. ISBN 0201021188. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)