Delayed choice quantum eraser question

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Discussion Overview

The discussion revolves around the delayed choice quantum eraser experiment, particularly focusing on the implications of measuring particles and the resulting interference patterns. Participants explore various test scenarios and their outcomes, questioning the relationship between measurement, erasure of results, and the appearance of interference patterns.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant proposes a new test sequence involving measuring particles and checking the wall at different steps, questioning whether interference patterns could change based on the order of these actions.
  • Another participant expresses confusion about the original question, suggesting that the interpretation of events is crucial to understanding the experiment.
  • It is noted that interference patterns are typically observed only in coincidence data, not directly on the wall where particles hit.
  • A participant raises a point about the nature of which-path information and its effect on interference patterns, suggesting that erasing marks could still yield an interference pattern.
  • Another participant presents a mathematical perspective on the outcomes based on different conditions of the slits, discussing the potential for interference and anti-interference patterns.
  • One participant acknowledges a clarification that separates marks based on which-path information is necessary to observe distinct patterns.
  • A later reply confirms the experimental results regarding the two different versions of "no-which-path" detection, inviting further theoretical explanation.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the results and the implications of measurement and erasure in the quantum eraser experiment. There is no consensus on the outcomes of the proposed test sequences or the nature of the interference patterns.

Contextual Notes

Some assumptions about the nature of measurements and their effects on interference patterns remain unresolved. The discussion also highlights the dependence on definitions of terms like "which-path" and "interference." Mathematical steps and the implications of different experimental setups are not fully explored.

cornernote
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I have a question about the delayed choice quantum eraser with the double split experiment. Forgive me if this is a silly question.I have seen the following:

TEST 1
1. shoot the particles & measure the result
2. erase the result
3. check the wall (whatever you shot the particle at)
= wall shows inteference pattern

TEST2
1. shoot the particles & measure the result
2. check the result
3. check the wall
= wall shows non inteference patternI would like to know the following result:

TEST 1
1. shoot the particles & measure the result
2. check the wall
3. erase the result
4. check the wall again

TEST 2
1. shoot the particles & measure the result
2. check the wall
3. check the result
4. check the wall again

Could you possibly get an inteference pattern at step 2 and then a non inteference pattern at step 4 or vise-versa?
 
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I don't know if bumps are allowed here, but I would really like to know the answer to this question.
 
Well I personally don't get your question. You need to frame it more precisely & I suspect you misunderstand parts of it. The only thing that changes is your interpretation of "what actually happened."

I just dug up a http://rapidshare.de/files/33406957/875.pdf.html" pdf article. Hope it helps.
 
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As far as I understand these experiments, the wall never shows an interference pattern. If you refer back to published results, you should notice that the interference fringes are only in the coincidence data.
 
Somethin i figure was weird about that experiment tho. U know which path the particle takes 50% of the time and don't the other 50%. Every time a particle hits the "wall" it makes a mark. U colour in all the marks that u have no which-path info for and they form an interference pattern. If u rubbed them out instead, wouldn't you also get an interference pattern? (Non inteference pattern - inteference pattern = inteference pattern) If so, does this mean the particles that you did get which-path info for still interfere?
 
Don't think so wiz. Possibilities:
1) slit A: gaussian
2) slit B: gaussian
3) slit A + slit B: fringes
4) slit A - slit B: antifringes
 
Awh! If i understand u right, that makes so much more sense. Actually solves a different question that was in my head too! Brian Green didnt mention u had to separate the marks u don't have which path info for in2 3 & 4 to get the patterns.

Are 3 & 4 the 2 different "no-which-path" detectors? Or have i completely misinterpreted ur post
 
Yes, that seems to be the experimental result, maybe someone else could explain the theory behind those two different versions of "no-which-path"?
 

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