Unknown Quantum States: The Quantum de Finetti Representation

  title={Unknown Quantum States: The Quantum de Finetti Representation},
  author={Carlton M. Caves and Christopher A. Fuchs and R. Schack},
  journal={Journal of Mathematical Physics},
We present an elementary proof of the quantum de Finetti representation theorem, a quantum analog of de Finetti’s classical theorem on exchangeable probability assignments. This contrasts with the original proof of Hudson and Moody [Z. Wahrschein. verw. Geb. 33, 343 (1976)], which relies on advanced mathematics and does not share the same potential for generalization. The classical de Finetti theorem provides an operational definition of the concept of an unknown probability in Bayesian… 

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