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Hi all,
Okay, I'm writing this post keeping in mind that FTL communication (or even backward in time communication) are impossible. However, I fail to understand why this would be impossible using the delayed choice quantum eraser, so my question is: where is the error in my logic here?
Imagine a copy of the delayed choice quantum eraser, except that the mirrors that decide whether the which-path information of the photon will be erased or not is not a beamsplitter but an actual mirror that can be added or removed.
In the traditional experiment, one would add or remove this mirror and inspect the joint detection rate to find interference or the lack thereof, depending on the presence of the mirror.
For photons that don't get entangled we'll see an interference pattern, and at some point there will be no (or very little) photons due to destructive interference. If the mirrors are removed, the which-path information is removed and the entangled photons will, too, form an interference pattern. Again, at the same point there will be no (or very little) photons.
If we add the mirrors the which path information is obtained and no interference pattern will emerge. So again measuring at the same point, there will be a few photons.
Conclusion (according to my logic): If measured at the point where destructive interference happens, the presence or absence of the mirrors can be detected. According to the logic of the delayed choice quantum eraser, the decision of whether the mirrors should be added or not can be made after the measurement is made, allowing backward in time communication.
Where's the error in my logic here?
Thanks in advance
Okay, I'm writing this post keeping in mind that FTL communication (or even backward in time communication) are impossible. However, I fail to understand why this would be impossible using the delayed choice quantum eraser, so my question is: where is the error in my logic here?
Imagine a copy of the delayed choice quantum eraser, except that the mirrors that decide whether the which-path information of the photon will be erased or not is not a beamsplitter but an actual mirror that can be added or removed.
In the traditional experiment, one would add or remove this mirror and inspect the joint detection rate to find interference or the lack thereof, depending on the presence of the mirror.
For photons that don't get entangled we'll see an interference pattern, and at some point there will be no (or very little) photons due to destructive interference. If the mirrors are removed, the which-path information is removed and the entangled photons will, too, form an interference pattern. Again, at the same point there will be no (or very little) photons.
If we add the mirrors the which path information is obtained and no interference pattern will emerge. So again measuring at the same point, there will be a few photons.
Conclusion (according to my logic): If measured at the point where destructive interference happens, the presence or absence of the mirrors can be detected. According to the logic of the delayed choice quantum eraser, the decision of whether the mirrors should be added or not can be made after the measurement is made, allowing backward in time communication.
Where's the error in my logic here?
Thanks in advance