Violation of Leggett-type inequalities in the spin-orbit degrees of freedom of a single photon

  title={Violation of Leggett-type inequalities in the spin-orbit degrees of freedom of a single photon},
  author={Filippo Cardano and Ebrahim Karimi and Lorenzo Marrucci and Corrado de Lisio and Enrico Santamato},
  journal={Physical Review A},
We report the experimental violation of Leggett-type inequalities for a hybrid entangled state of spin and orbital angular momentum of a single photon. These inequalities give a physical criterion to verify the possible validity of a class of hidden-variable theories, originally named "crypto non-local", that are not excluded by the violation of Bell-type inequalities. In our case, the tested theories assume the existence of hidden variables associated with independent degrees of freedom of the… 

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