delayed choice quantum eraser question

[cornernote]

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 partical 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 pattern


I 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?

[cornernote]

I don't know if bumps are allowed here, but I would really like to know the answer to this question.

[Thrice]

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 Science (http://rapidshare.de/files/33406957/875.pdf.html) pdf article. Hope it helps.

[cesiumfrog]

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.

[blackwizard]

Somethin i figure was weird about that experiment tho. U know which path the particle takes 50% of the time and dont 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?

[cesiumfrog]

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

[blackwizard]

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 seperate the marks u dont hav which path info for in2 3 & 4 to get the patterns.

Are 3 & 4 the 2 different "no-which-path" detectors? Or hav i completely misinterpreted ur post

[cesiumfrog]

Yes, that seems to be the experimental result, maybe someone else could explain the theory behind those two different versions of "no-which-path"?