From: John K Clark (jonkc@att.net)
Date: Fri May 10 2002 - 11:01:01 MDT
"scerir" <scerir@libero.it>
> D3 D2
> | |
> | |
> | source of |
> D4 -- -- -- / <-- two entangled --> \ -- -- -- D1
> photons
>
> interferometer 2 interferometer 1
> Hmmm. Let us say this way. "If" I put a detector in D2 this
> detector can tell if the photon #1 is there or if the photon
> #1 is in D1. But in both cases (100%) the interference
> inside the interferometer 1 is destroyed. So, "if" I put
> a detector in D2, even if I do not read it, I destroy the
> interference.
> Now the next question, imo, is: if a put a detector in D2,
> I also destroy the interference inside the interferometer 2,
> where the entangled photon #2 is passing through?
Ok, I think I understand what you're driving at but it won't work, you will
detect interference in the second interferometer unless you have detectors
at D3 or D1, what happened at D1 or D2 doesn't matter in the experiment as
set up. Not everything can be entangled, the polarization and momentum of
two photons can be, but neither of these attributes by themselves can
command a interference effect in the machine you describe.
Let me give you my set up: An entangles photon is heading toward me, the
other one is heading to you far away, I place my polarizing filter in a
random orientation, there is a 50-50 chance the photon will make it through
my filter, if it does and if you place your filter at the same angle then
there is a 100% chance the photon will get through your filter. If you turn
your filter 90 degrees from mine then there is a zero chance it will get
through. More generally the square of the cosign of the angle between the 2
polarizing filters is proportional to the probability that your photon will
make it through your filter. So if I could somehow command my photon and
tell it to pass through my filter or be stopped by it then I could make a
faster than light telegraph, but I can't, it's random. I've instantly
changed things in your receiver but I've sent no message, it will just look
random to you until we communicate at light speed and see that it was not.
John K Clark jonkc@att.net
>
> This question has, maybe, something to do with the time-energy
> (Heisenberg's) relation, of course for both the entangled photons,
> bounded in a 'singlet' state.
>
> If the symmetry of the system is perfect (interferometer 1
> & interferometer 2 are identical, photon # 1 & photon #2
> have the same timing) we can destroy interference inside
> interferometer 2 if we put a detector inside interferometer
> 1 in D2. At least this is my bet! That is because each of
> the two entangled photons behaves, inside his interferometer,
> exactly like the other.
>
> (Still thinking about the rest of those questions).
>
> s.
>
>
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