Positive phase space transformation incompatible with classical physics.
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 positive Wigner function and performing only operationally local transformations that preserve this positivity, can nonetheless violate Bell's inequality. Such operationally local transformations are realized using entangled ancillae.
Son
Wonmin
W
The School of Physics and Astronomy, University of Leeds, LS2 9JT Leeds, United Kingdom.
Kofler
Johannes
J
Kim
M S
MS
Vedral
Vlatko
V
Brukner
Caslav
C