754 research outputs found
Superluminal hidden communication as the underlying mechanism for quantum correlations: constraining models
Since Bell's theorem, it is known that quantum correlations cannot be
described by local variables (LV) alone: if one does not want to abandon
classical mechanisms for correlations, a superluminal form of communication
among the particles must be postulated. A natural question is whether such a
postulate would imply the possibility of superluminal signaling. Here we show
that the assumption of finite-speed superluminal communication indeed leads to
signaling when no LV are present, and more generally when only LV derivable
from quantum statistics are allowed. When the most general LV are allowed, we
prove in a specific case that the model can be made again consistent with
relativity, but the question remains open in general.Comment: 5 pages, 1 figure. For the Proceedings of the Conference DICE 2004
(Piombino, 1-4 Sept. 2004
Coexistence of Quantum Theory and Special Relativity in signaling scenarios
The coexistence between Quantum Mechanics and Special Relativity is usually
formulated in terms of the no-signaling condition. Several authors have even
suggested that this condition should be included between the basic postulates
of Quantum Theory. However, there are several scenarios where signaling is, in
principle, possible: based on previous results and the analysis of the relation
between unitarity and signaling we present an example of a two-particle
interferometric arrangement for which the dynamics is, in principle, compatible
with superluminal transmission of information. This type of non-locality is not
in the line of Bell's theorem, but closer in spirit to the one-particle
acausality studied by Hegerfeldt and others. We analyze in this paper the
meaning of this non-locality and how to preserve the coexistence of the two
fundamental theories in this signaling scenario.Comment: See also the comment by G C Hegerfeldt in the online version of the
journal, including more reference
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