Speaker
Dr
Petros Wallden
(Heriot-Watt University)
Description
Abstract: Quantum theory allows sets of probabilities between
spacelike separated parties that cannot be recovered from a local
(realistic) theory as it is shown by violations of Bell's
inequalities. The violation of Bell's inequalities is equivalent with
proving that there does not exist a joint probability distribution for
all the different (unrealised) alternatives. The non-existence of a
joint probability distribution implies that the outcomes are
contextual. Inspired by path integral formulations of quantum theory,
we define a generalisation of the non-contextuality condition that
includes all correlations that quantum theory predicts. The condition
is the existence of a joint strongly positive quantum measure. This
leads to the Q^{1+AB} condition of the NPA hierarchy. Interestingly,
the set of probabilities allowed by this condition are more than those
allowed by quantum theory, coincide with the "almost quantum
correlations" conjectured as the set of real correlations by Navascues
et al (2014) and satisfies all the known information theoretic
physical principles that have been proposed (such as Non-trivial
communication complexity, Local Orthogonality, etc). Therefore, this
extension of quantum theory appears natural both from histories
perspective and from quantum information perspective.
- F. Dowker, J. Henson and P. Wallden, New J. Phys. (in press)
arxiv:1311.6287.
