[ExI] Cramer on impossibility of FTL communication

[scerir at alice.it]

An Inquiry into the Possibility of Nonlocal Quantum Communication

Authors: 
John G. Cramer,  Nick Herbert

http://arxiv.org/abs/1409.5098
Abstract: 
The possibility of nonlocal quantum 
communication is considered. We investigate three gedankenexperiments
that have 
variable entanglement: (1) a 4-detector polarization-entangled system, (2) a 4-
detector 
path-entangled system, and (3) a 3-detector path-entangled system 
that uses an innovative optical mixer 
to combine photon paths. 
A new quantum 
paradox is reviewed in which the presence or absence of an interference pattern 
in 
a path-entangled two photon system, controlled by measurement choice, is a 
potential nonlocal signal. 
We show that for the cases considered, even when 
interference patterns can be switched off and on, 
there is always a "signal" 
interference pattern and an "anti-signal" interference pattern that mask 
any 
observable interference when they are added, even when entanglement and 
coherence are 
simultaneously present. This behavior can be attributed to what 
in the literature has been called 
"the complementarity of one-particle and two-
particle interference".

Important papers about "the complementarity of one-
particle and two-particle interference" are:

http://arxiv.org/abs/quant-ph/0112065
http://physics.gmu.edu/~rubinp/courses/123/superpositionprinciple.pdf
That is 
to say it seems not possible to use quantum entanglement (i.e. two-photon

position/momentum quantum entanglement) to create (or not) interference 
patterns
on a screen (or whatever) at a distance. 

Of course we know there are 
theorems (i.e. by Ghirardi, etc.) showing we cannot use
quantum entanglements 
for FTL communication. But we also know that theorems
sometimes are circular. 
It is possible that formalisms used in this theorems 
(i.e. tensor product) 
already do not allow FTL communication (as pointed out by
Kennedy)

http://philpapers.org/rec/KENOTE