[ExI] R: Re: Re: R: Re: R: Re: Cramer on impossibility of FTL communication

[scerir at alice.it]

Adrian Tymes wrote:
The common cause is their entanglement, which happens at their manufacture.
Or can you find me anything that directly counters this explanation?

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The problem I see is this: "happens at their manufacture." But when does it 
occur?

R. H. Dicke invented a peculiar set-up. It involves 2 distant atoms, A and B. 
These atoms are in the |0> ground state and are shone by a weak laser beam 
tuned to the |0> ----> |2> transition energy (|2> is  an excited state).

Now if a detector detects a single photon, of the |2> -----> |1>  transition 
energy, the following entangled state ensues:

|1, (A)> |2, (B)> + |2, (A)> |1, (B)>

Since only one photon is detected, the uncertainty about the photon’s origin 
suffices to make the two atoms entangled. 

Unlike the ordinary entanglement creation, where the two particles have 
interacted *earlier*, here the only common event lies *in the future*.

Entanglement is then achieved as a consequence of two facts: first, the 
impossibility to determine from the detection event which atom emitted the 
photon, second, the projection postulate in quantum mechanics, which indicates 
that, after the detection, the state of the atoms is projected onto the one 
which is compatible with the outcome of the measurement.