Physics Help Forum Double slits experiment with one or two detectors

 Quantum Physics Quantum Physics Help Forum

 May 16th 2017, 03:33 AM #1 Member   Join Date: Apr 2017 Posts: 46 Double slits experiment with one or two detectors Does it matter if there is a detector in every of the two splits, or just in one of them? Will there be any difference? I wonder if I asked the question correctly. I mean will the result of the experiment be different if we stick a detector only in one slit, and the other slit will be undetected. Last edited by Fox333; May 16th 2017 at 11:15 AM. Reason: adding information
 May 16th 2017, 02:21 PM #2 Senior Member   Join Date: Nov 2013 Location: New Zealand Posts: 538 A detector at either slit seems to enough to destroy the interference pattern
 May 17th 2017, 12:33 AM #3 Senior Member   Join Date: Nov 2013 Location: New Zealand Posts: 538 This video with english subtitles should help
 May 17th 2017, 12:57 AM #4 Member   Join Date: Apr 2017 Posts: 46 Thanks. The other question: let's say there is a detector in the left slit. Is there 50/50 % probability to detect the particle in the left split? So, 50% of experiments will end with detecting the particle in the left slit, and 50% with detecting nothing, but without observing the interference pattern?
 May 17th 2017, 04:22 AM #5 Senior Member   Join Date: Nov 2013 Location: New Zealand Posts: 538 My understanding is a detector on either side will destroy the interference pattern as shown in the above animation clip. I assume that particles go through each slit with equal probability or 50/50.
 May 17th 2017, 05:20 AM #6 Member   Join Date: Apr 2017 Posts: 46 There could be two possibilities: 1) assuming the "ordinary" logic: having a detector in the left slit, we will observe the particle in the half of cases. In the other half the particle will leave undetected. We can only assume that it leaves throw the right slit. No interference pattern. 2) alternative possibility: we will always detect the particle in the only left detector. No interference pattern, but we can detect the particle in the 100% of cases.
 May 17th 2017, 11:47 AM #7 Senior Member     Join Date: Jun 2016 Location: England Posts: 692 Some of you will probably disagree... I personally favour an interpretation that leans toward the De-Broglie Bohm pilot wave theory (rather than the Copenhagen Interpretation). My interpretation is that every particle contributes to a probability field, within which the probability of a particle existing at a given position (and time) is dependent on the relative situations of all the other particles around it. In order to produce the double slit effect one has to quite carefully arrange things such that the probability field the particle traverses allows for two essentially equally probable paths. It is impossible to introduce a detector (no matter how subtle) and maintain that finely balanced probability field. __________________ ~\o/~
 May 17th 2017, 12:16 PM #8 Member   Join Date: Apr 2017 Posts: 46 Woody, I see, indeed, it's one of possible interpretations. Personally, I'm interested more about the real experiment and its outcome. I mean the double slit experiment with only one detector: have it ever been done? If yes, was the particle detected in 50 or 100 % cases?
 May 17th 2017, 12:39 PM #9 Member   Join Date: Apr 2017 Posts: 46 There is an animation of the experiment with one detector on minute 9 of the video, was there a real experiment like that? If it was really like that, so there is a question: why the pattern disappears if the particle wasn't detected? We can't know that it passed from the other slit, we can only assume that. We don't have any observed fact, we only have an assumption. But it breaks the pattern anyway. Why?
May 17th 2017, 03:46 PM   #10
Senior Member

Join Date: Nov 2013
Location: New Zealand
Posts: 538
 Originally Posted by Fox333 There could be two possibilities: 1) assuming the "ordinary" logic: having a detector in the left slit, we will observe the particle in the half of cases. In the other half the particle will leave undetected. We can only assume that it leaves throw the right slit. No interference pattern. 2) alternative possibility: we will always detect the particle in the only left detector. No interference pattern, but we can detect the particle in the 100% of cases.
I don't think #2 is correct. We would still see two bands on the screen indicating that the particle at various times went through either slit. However, we only detected it in the left.

 Thread Tools Display Modes Linear Mode

 Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post pranimaboity2050 Advanced Optics 0 Apr 10th 2015 11:55 PM MMM Quantum Physics 1 Mar 13th 2015 01:34 PM harve Advanced Waves and Sound 7 Dec 2nd 2014 10:57 AM mola Advanced Optics 1 May 18th 2009 01:35 AM Sean12345 Nuclear and Particle Physics 2 Apr 16th 2008 07:31 AM