# The Choi–Jamiołkowski isomorphism and covariant quantum channels

@article{Haapasalo2021TheCI, title={The Choi–Jamiołkowski isomorphism and covariant quantum channels}, author={Erkka Haapasalo}, journal={Quantum Studies: Mathematics and Foundations}, year={2021} }

A generalization of the Choi-Jamiolkowski isomorphism for completely positive maps between operator algebras is introduced. Particular emphasis is placed on the case of normal unital completely positive maps defined between von Neumann algebras. This generalization is applied especially to the study of maps which are covariant under actions of a symmetry group. We highlight with the example of, e.g., phase-shift-covariant quantum channels the ease of this method in particular in the case of a…

## 2 Citations

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This manuscript shows that two seemingly different aspects of quantum incompatibility: the quantum marginal problem of states and the incompatibility on the level of quantum channels are in one-to-one correspondence with each other.

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We study generating joint measurements by operating on the input quantum state with a broadcasting channel followed by local measurements on the two outputs of the broadcasting channel. Although, due…

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