Figure 1

The structure of a general discrimination strategy for classical channels. This example makes four channel evaluations, each illustrated by a box labeled $M_a$, but in general any finite number $n$ of evaluations may be considered. Each arrow represents a register that may be in a random mixture over some finite set of classical states and the boxes labeled $F_0$, $F_1$, $F_2$, and $F_3$ represent arbitrary functions (or random processes) that must be independent of the value $a\in \{0,1\}$ that indicates which of the two channels is given.Reuse & Permissions