title: Experimental quantum process discrimination.
abstract: Discrimination between unknown processes chosen from a finite set is experimentally shown to be possible even in the case of nonorthogonal processes. We demonstrate unambiguous deterministic quantum process discrimination of nonorthogonal processes using properties of entanglement, additional known unitaries, or classical communication. Single qubit measurement and unitary processes and multipartite unitaries (where the unitary acts nonseparably across two distant locations) acting on photons are discriminated with a confidence of >or=97% in all cases.
authors.affiliation: Centre for Quantum Photonics, H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Bristol, BS8 1UB, United Kingdom.
authors.forename: Anthony
authors.initials: A
authors.lastname: Laing
authors.forename: Terry
authors.initials: T
authors.lastname: Rudolph
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: O'Brien