Suppose that we have a light emission apparatus capable of emitting only one photon. Then we set this photon to pass in a double slit apparatus and emerge in a black screen such that when it is absorbed the photon lives a mark.

My question is: if we close one of the slits, and set a sufficiently large amount of photons perform the above apparatus what we will see in the screen is a normal distribution or a interference pattern? If we set light, instead of photons, we see an interference pattern, correct? But does the one-photon change, changes the way that the experiments shows itself, showing a more 'particle' than 'wave' characteristic of light?

  • $\begingroup$ When you close one of the slits, you cease to have a double-slit experiment. You now have a single-slit experiment where light only has one possible path, so you will not see interference patterns, whether you use one photon or many. $\endgroup$
    – Cort Ammon
    Commented Jan 16, 2018 at 17:23
  • $\begingroup$ @CortAmmon What about the single-slit interference pattern? $\endgroup$
    – Bill N
    Commented Jan 16, 2018 at 17:26
  • $\begingroup$ @BillN As in diffraction? $\endgroup$
    – Cort Ammon
    Commented Jan 16, 2018 at 17:31
  • $\begingroup$ The experiment you describe is easily repeated. Google for "one photon at a time". $\endgroup$ Commented Jan 16, 2018 at 17:33
  • 1
    $\begingroup$ A single slit will produce a sinc pattern on the screen $\endgroup$ Commented Jan 16, 2018 at 17:33

1 Answer 1


First off - what you describe is a single-slit experiment, not a double-slit experiment. As soon as you know which slit the photons go through, it is no longer a double-slit experiment.

Back to your question. You make a difference between 'light' and 'photons'. I assume that by light you refer to a description in the 'wave-picture'. Note that single photons are also light. The light source simply has a very low intensity. As a consequence - even if you send your photons through the slit one at a time: The outcome will be the same as with what you called 'light'. You simply have to send many photons through the slit.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.