FTL communication via delayed choice measurement

[Alex Torres]

Walborn states that at the beginning of section III. In the polarization entangled BBO version of the experiment he uses afterwards, the incoming light is not polarized linearly anymore and there is no direct interference pattern left

Ok got it...

Just gave that link by mistake, the following gives a better layman's description, see under the caption "Double slit interference", he performs a test for interference in his setup before touching in anyway the polarization of the entangled photons.

https://files.acrobat.com/a/preview/abdaa0fc-2e1a-4689-97f8-8d866fe89a63

Think he just wanted to be sure the SPDC process was not affecting the interference pattern in anyway.

But,...let us stop right there,...

Assume detector Dp is replaced by another detector which is exactly the same as detector Ds.

The question is... will Dp(assuming was replaced as described above ) show the same interference pattern as it happens to be in Ds??

 

[Alex Torres]

...Still, we might be able to do some FTL signaling with a very simple setup and some basic statistical concepts ...

Using the realization of Asher Peres thought experiment dubbed "steering into the past"...we give Alice and Bob on Earth an atomic clock and another one to Victor on Pluto...
...both clocks are coordinated with settings telling the exact minute an experiment starts and ends so all three, Bob Alice and Victor will know the beginning and the end of any single experiment run...

A single experiment run can consist of the following: ...a single batch of 100 pairs of entangled photons that both Alice and Bob receive, with Victor projecting all them into an entangled state (quantum correlation)...with each measurement from Victor being delayed by the time/distance between Earth and Pluto...

Under these conditions each pair of photons received by Alice and Bob will correlate in a way that if Alice's quantum state is 1 Bob will be 100% certain that his is 0 and vice versa...so by the end of the experiment run 100 pairs of entangled photons received by Alice and Bob with 100% correlation for each pair means Victor projected the whole batch in an entangled state...this whole batch counts as a 1...then it means Victor signaled a 1...

...for signaling a 0... Victor will let Alice and Bob receive the whole batch of entangled pairs of photons with classical correlations within a single experiment run...that means, there will always be less than 100% certainty that all pairs received by Alice and Bob under that single batch will correlate... with that probability result Alice and Bob on Earth will be certain Victor did not projected an entangled state for that batch..

 

[Deepblu]

Under these conditions each pair of photons received by Alice and Bob will correlate in a way that if Alice's quantum state is 1 Bob will be 100% certain that his is 0 and vice versa...so by the end of the experiment run 100 pairs of entangled photons received by Alice and Bob with 100% correlation for each pair means Victor projected the whole batch in an entangled state...this whole batch counts as a 1...then it means Victor signaled a 1...

...for signaling a 0... Victor will let Alice and Bob receive the whole batch of entangled pairs of photons with classical correlations within a single experiment run...that means, there will always be less than 100% certainty that all pairs received by Alice and Bob under that single batch will correlate... with that probability result Alice and Bob on Earth will be certain Victor did not projected an entangled state for that batch..

Alice and Bob will have to wait for all the photons to arrive from Pluto first then do the measurements then compare their results, so they have to wait long time much longer than speed of light to tell what vector did on his end.

When Victor wants to change signalling from 1 to 0, Alice and Bob will have to wait at least 5.5 hours (the time needed for light to travel from Pluto to Earth) first before receiving all the photons.

Why do you insist that FTL communication is possible?! You can't send information by observation .. that's it .. a very simple truth!

 

[DrClaude]

Why do you insist that FTL communication is possible?! You can't send information by observation .. that's it .. a very simple truth!

This is a good place to end this thread.