Unambiguous discrimination of mixed quantum states: Optimal solution and case study
Matthias Kleinmann, Hermann Kampermann, Dagmar Bruß · Physical Review A · 2010
We present a generic study of the unambiguous discrimination between two mixed quantum states. We derive operational optimality conditions and show that the optimal measurements can be classified according to their rank. In Hilbert space dimensions less than or equal to $5$, this leads to the complete optimal solution. We demonstrate our method with a physical example, namely, the unambiguous comparison of $n$ quantum states, and find the optimal success probability.