Nonsequential positive-operator-valued measurements on entangled mixed states do not always violate a Bell inequality

  title={Nonsequential positive-operator-valued measurements on entangled mixed states do not always violate a Bell inequality},
  author={Jonathan Barrett},
  journal={Physical Review A},
  • J. Barrett
  • Published 7 July 2001
  • Physics
  • Physical Review A
We present a local-hidden-variable model for positive-operator-valued measurements (an LHVPOV model) ) on a class of entangled generalized Werner states, thus demonstrating that such measurements do not always violate a Bell-type inequality. We also show that, in general, if the state ρ' can be obtained from p with certainty by local quantum operations without classical communication, then an LHVPOV model for the state p implies the existence of such a model for p'. 
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