Delayed Choice Quantum Eraser Experiment Results

[Suleyman EROGLU]

Hello everyone.
I want to ask some questions about dcqe experiments results which are bugging my mind. It is so hard to find reliable sources in my native language so I'm here. Also sorry for my scuffed english.
Assuming we all know the famous experiment setup, I am directly passing to the questions.
- Even if the particle hits the screen before it's entangled twin reaches the detector (which gives us the information of which slit is particle came from), there is slit pattern on screen. First I thought they communicate each other beyond time but some says it has nothing with sending information past or future. So if it is, would you kindly explain how it works.
- When a quantum eraser added to system (which makes lose the information of particles came from) we see interference pattern. So it has nothing with the measurement device but the exact information of particles. So how particles know that we gathered information true or not?
Thank you.

 

[Nugatory]

Assuming we all know the famous experiment setup...

There are several, some which have actually been done and some of which are thought experiments, You'll have to tell us exactly which one you're thinking about here.

 

[Suleyman EROGLU]

I've talked about this one.

 

[Cthugha]

- When a quantum eraser added to system (which makes lose the information of particles came from) we see interference pattern. So it has nothing with the measurement device but the exact information of particles. So how particles know that we gathered information true or not?

This is incorrect and a common wrong assumption about the experiment. You never see an interference pattern on the screen in the DCQE experiment. You can only see the interference pattern in the coincidence counts between both detectors. This is crucial. The rough story to what happens is: correlation. The broad slit pattern is basically a superposition of two interference patterns, which are out of phase with each other. Photons that tend to end up on the peaks of the first interference pattern will have entangled twin photons on the other side that tend to end up on one of the detectors with erased which-way information preferentially. Photons that tend to end up on the peaks of the second interference pattern will have entangled twin photons on the other side that tend to end up on the other detector with erased which-way information preferentially. Photons that end up on the detectors which yield which-way information, end up on each of the two interference patterns with equal probability, which yields the slit pattern. That is all. If you want to understand the physics in a more-than-handwaving way, you need to read the actual publications and do the math yourself. It is not that complicated.

 

[msumm21]

Regarding the histograms formed by the measurements of where the photon it the screen. Is it true that the histogram for all cases where which-path was measured (both A and B slits combined) matches the histogram for all cases where which-path was NOT measured?

It seems this must be true, right?