In contrast to the many-to-one and quadratic nature of correspondence in the conventional representation of quantum channels, such as the operator-sum or the unitary representation, we present a one-to-one and linear (affine) parametrization of quantum channels. This parametrization enables us to visualize the convex structure of the space of quantum channels. To demonstrate its usefulness, we apply it to the analysis of quantum binary channels.

• Received 6 October 1998

DOI:https://doi.org/10.1103/PhysRevA.59.3290