title: Ancilla-assisted calibration of a measuring apparatus.
abstract: A quantum measurement can be described by a set of matrices, one for each possible outcome, which represents the positive operator-valued measure (POVM) of the sensor. Efficient protocols of POVM extraction for arbitrary sensors are required. We present the first experimental POVM reconstruction that takes explicit advantage of a quantum resource, i.e., nonclassical correlations with an ancillary state. A POVM of a photon-number-resolving detector is reconstructed by using strong quantum correlations of twin beams generated by parametric down-conversion. Our reconstruction method is more statistically robust than POVM reconstruction methods that use classical input states.
authors.affiliation: Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, Torino 10135, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Brida
authors.forename: L
authors.initials: L
authors.lastname: Ciavarella
authors.forename: I P
authors.initials: IP
authors.lastname: Degiovanni
authors.forename: M
authors.initials: M
authors.lastname: Genovese
authors.forename: A
authors.initials: A
authors.lastname: Migdall
authors.forename: M G
authors.initials: MG
authors.lastname: Mingolla
authors.forename: M G A
authors.initials: MG
authors.lastname: Paris
authors.forename: F
authors.initials: F
authors.lastname: Piacentini
authors.forename: S V
authors.initials: SV
authors.lastname: Polyakov