Coexistence of quantum operations
Teiko Heinosaari, Daniel Reitzner, Peter Stano, Mário Ziman · Journal of Physics A Mathematical and Theoretical · 2009
Quantum operations are used to describe the observed probability distributions and conditional states of the measured system. In this paper, we address the problem of their joint measurability (coexistence). We derive two equivalent coexistence criteria. The two most common classes of operations—Lüders operations and conditional state preparators—are analyzed. It is shown that Lüders operations are coexistent only under very restrictive conditions, when the associated effects are either proportional to each other or disjoint.