title: Entanglement is not necessary for perfect discrimination between unitary operations.
abstract: We show that a unitary operation (quantum circuit) secretly chosen from a finite set of unitary operations can be determined with certainty by sequentially applying only a finite amount of runs of the unknown circuit. No entanglement or joint quantum operations are required in our scheme. We further show that our scheme is optimal in the sense that the number of the runs is minimal when discriminating only two unitary operations.
authors.affiliation: State Key Laboratory of Intelligent Technology and Systems, Department of Computer Science and Technology, Tsinghua University, Beijing, China, 100084. dry@tsinghua.edu.cn
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