1. Jun 16, 2011

### nouveau_riche

"consider the same interference experiment,the interference pattern produced is used to illuminate the next source in series,which then produces a new interference pattern,this gets cascaded say 10 times and the final interference pattern is obtained on the wall.
now ,the observer, observing the final interference pattern is not known of the fact that there's another observer measuring the particle position in the first stage of interference,and viceversa

will an interference pattern b seen by the observer ,observing it at the last stage?
and if u think the experiment is not possible then provide a reason for the same

2. Jun 17, 2011

### nouveau_riche

Last edited: Jun 17, 2011
3. Jun 17, 2011

### nouveau_riche

i think there really is no certain answer

4. Jun 17, 2011

### DrChinese

I question if anyone understands what you mean by cascaded interference. Basically, there is no superposition if it is possible to determine any which path information, regardless of the particular setup.

5. Jun 17, 2011

### San K

the moment you measure the particle position in the first stage (or any stage or anywhere), the interference will disappear.......starting with that particular photon....even if it has passed 2 or 5 or 10 slits already.....(assuming we are sending photons one by one)....

thus this won't work......

or in other words

for whichever ("travelling/experimental/sample") photon(s) you do the measurement for......it's position would correspond to ......building a single blob pattern (non-interference pattern) instead of interference pattern.....

6. Jun 18, 2011

### nouveau_riche

but if have a photon having high uncertainity in position then there might be the probability that localising the particle at say 2nd stage would produce an interference pattern at atleast 3rd stage regardless of the fact of being showing it's particle nature

7. Jun 18, 2011

### San K

the "collapse of the wave function" is instantaneous, the moment you detect it, say at the 2nd stage, it "becomes" a particle...

however if it goes through slits on the 3rd stage and we don't find which-way....yes...you will get an interference pattern...

so now you have which-way in 2nd slit and interference pattern in screen at 3rd stage......

you now have which-way and interference pattern.....so to speak/in a sense.....however these are separate events...:)

8. Jun 19, 2011

### nouveau_riche

so ..if i can get the interference pattern at later stages ...the problem become cumbersome..
the observer observing the interference pattern at last stage will never be aware of the fact the particle has shown it's particle nature to any observer i.e no effect of previous interaction of observer localising it