Positive Phase Space Transformation Incompatible with Classical Physics

Wonmin Son, Johannes Kofler, Myungshik Kim, Vlatko Vedral, Caslav Brukner

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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.
Original languageEnglish
Article number110404
Number of pages4
JournalPhysical Review Letters
Issue number11
Publication statusPublished - 2009

Austrian Fields of Science 2012

  • 103026 Quantum optics

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