Necessary and sufficient conditions on measurements of quantum channels

@article{Burniston2020NecessaryAS,
  title={Necessary and sufficient conditions on measurements of quantum channels},
  author={John Burniston and Michael Grabowecky and Carlo Maria Scandolo and Giulio Chiribella and Gilad Gour},
  journal={Proceedings of the Royal Society A},
  year={2020},
  volume={476}
}
Quantum supermaps are a higher-order genera- lization of quantum maps, taking quantum maps to quantum maps. It is known that any completely positive and trace non-increasing (CPTNI) map can be performed as part of a quantum measurement. By providing an explicit counterexample we show that, instead, not every quantum supermap sending a quantum channel to a CPTNI map can be realized in a measurement on quantum channels. We find that the supermaps that can be implemented in this way are exactly… Expand

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