title: Perfect distinguishability of quantum operations.
abstract: We provide a feasible necessary and sufficient condition for when an unknown quantum operation (quantum device) secretly selected from a set of known quantum operations can be identified perfectly within a finite number of queries, and thus complete the characterization of the perfect distinguishability of quantum operations. We further design an optimal protocol which can achieve the perfect discrimination between two quantum operations by a minimal number of queries. Interestingly, we find that an optimal perfect discrimination between two isometries is always achievable without auxiliary systems or entanglement.
authors.affiliation: State Key Laboratory of Intelligent Technology and Systems, Tsinghua National Laboratory for Information Science and Technology, Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China. Runyao.Duan@uts.edu.au
authors.forename: Runyao
authors.initials: R
authors.lastname: Duan
authors.forename: Yuan
authors.initials: Y
authors.lastname: Feng
authors.forename: Mingsheng
authors.initials: M
authors.lastname: Ying