 Quantum state exclusion

A task in which a quantum measurement outputs a label of a preparation that can be ruled out. If preparations are ${\rho }_j$ and the outcome labelled $j$ has effect $E_j$, error-free exclusion requires $\mathrm{Tr}(E_j{\rho }_j)=0$ for every $j$, together with $E_j\ge 0$ and ${\sum }_j{E}_j=I$. A family admitting a complete error-free exclusion measurement consists of antidistinguishable quantum states. Exclusion need not identify the actual preparation.