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A de Finetti Representation Theorem for Quantum Process Tomography

Christopher A. Fuchs·Ruediger Schack·Petra F. Scudo
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Abstract

In quantum process tomography, it is possible to express the experimenter's prior information as a sequence of quantum operations, i.e., trace-preserving completely positive maps. In analogy to de Finetti's concept of exchangeability for probability distributions, we give a definition of exchangeability for sequences of quantum operations. We then state and prove a representation theorem for such exchangeable sequences. The theorem leads to a simple characterization of admissible priors for quantum process tomography and solves to a Bayesian's satisfaction the problem of an unknown quantum operation.

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Christopher A. Fuchs, Ruediger Schack, Petra F. Scudo. 2003-07-28. A de Finetti Representation Theorem for Quantum Process Tomography. https://doi.org/10.1103/physreva.69.062305

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