title: Implementation of generalized quantum measurements for unambiguous discrimination of multiple non-orthogonal coherent states.
abstract: Generalized quantum measurements implemented to allow for measurement outcomes termed inconclusive can perform perfect discrimination of non-orthogonal states, a task which is impossible using only measurements with definitive outcomes. Here we demonstrate such generalized quantum measurements for unambiguous discrimination of four non-orthogonal coherent states and obtain their quantum mechanical description, the positive-operator valued measure. For practical realizations of this positive-operator valued measure, where noise and realistic imperfections prevent perfect unambiguous discrimination, we show that our experimental implementation outperforms any ideal standard-quantum-limited measurement performing the same non-ideal unambiguous state discrimination task for coherent states with low mean photon numbers.
authors.affiliation: Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. fbecerra@umd.edu
authors.forename: F E
authors.initials: FE
authors.lastname: Becerra
authors.forename: J
authors.initials: J
authors.lastname: Fan
authors.forename: A
authors.initials: A
authors.lastname: Migdall