Single-shot discrimination of quantum unitary processes

Understand

We formulate minimum-error and unambiguous discrimination problems for quantum processes in the language of process positive operator valued measures (PPOVM).

• In this framework we present the known solution for minimum-error discrimination of unitary channels.
• We derive a "fidelity-like" lower bound on the failure probability of the unambiguous discrimination of arbitrary quantum processes.
• This bound is saturated (in a certain range of apriori probabilities) in the case of unambiguous discrimination of unitary channels.