

Quantum Discord,Chsh Inequality and Hidden Variables: Critical Reassessment of HiddenVariables Models





نویسنده

Fujikawa K.

منبع

Malaysian Journal Of Mathematical Sciences  2014  دوره : 8  شماره : S  صفحه:27 45



چکیده

Hiddenvariables models are critically reassessed. it is first examined if the quantum discord is classically described by the hiddenvariable model of bell in the hilbert space with d = 2. the criterion of vanishing quantum discord is related to the notion of reduction and,surprisingly,the hiddenvariable model in d = 2,which has been believed to be consistent so far,is in fact inconsistent and excluded by the analysis of conditional measurement and reduction. the description of the full contents of quantum discord by the deterministic hiddenvariables models is not possible. we also reexamine chsh inequality. it is shown that the wellknown prediction of chsh inequality b ≤ 2 for the chsh operator b introduced by cirel'son is not unique. this nonuniqueness arises from the failure of linearity condition in the noncontextual hiddenvariables model in d = 4 used by bell and chsh,in agreement with gleason's theorem which excludes d = 4 noncontextual hiddenvariables models. if one imposes the linearity condition,their model is converted to a factored product of two d = 2 models which describes quantum mechanical separable states. the chsh inequality thus does not test the hiddenvariables model in d = 4. this observation is consistent with an application of the chsh inequality to quantum cryptography by ekert,which is based on mixed separable states without referring to dispersionfree representations. as for hiddenvariables models,there exist no viable local noncontextual models in any dimensions.



آدرس

Riken Nishina Center, Japan














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