Positive phase space transformation incompatible with classical physics.

Journal article

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.

Authors: Son, W; Kofler, J; Kim, MS; Vedral, V; Brukner, C

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 102
• Issue: 11
• Pages: 110404
• Publication date: 2009-03-01
• DOI: 10.1103/physrevlett.102.110404
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: quant-ph