Positive phase space transformation incompatible with classical physics.

@article{Son2009PositivePS,
  title={Positive phase space transformation incompatible with classical physics.},
  author={Wonmin Son and Johannes Kofler and M. S. Kim and Vlatko Vedral and {\vC}aslav Brukner},
  journal={Physical review letters},
  year={2009},
  volume={102 11},
  pages={
          110404
        }
}
Bell conjectured that a positive Wigner function does not allow violation of the inequalities imposed by local hidden variable theories. A requirement for this conjecture is "when phase space measurements are performed." We introduce the theory-independent concept of "operationally local transformations" which refers to the change of the switch on a local measurement apparatus. We show that two separated parties, performing only phase space measurements on a composite quantum system with a… 

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