Canonical structure of A and B maps

In their seminal 1961 paper, Sudarshan, Mathews and Rau investigated properties of the dynamical A B maps acting on n-dimensional quantum systems. The nature in open system evolutions has attracted great deal attention later years. However, novel paper not received its due attention. this tutorial article, we review forms associated with dynamics finite dimensional particular, investigate a canonical structure form establish equivalence form. We show that captures completely positive (not positive) succinct manner. This feature is illustrated through physical examples qubit channels.Quanta 2021; 10: 34–41.