title: Universal Continuous-Variable State Orthogonalizer and Qubit Generator.
abstract: We experimentally demonstrate a universal strategy for producing a quantum state that is orthogonal to an arbitrary, infinite-dimensional, pure input one, even if only a limited amount of information about the latter is available. Arbitrary coherent superpositions of the two mutually orthogonal states are then produced by a simple change in the experimental parameters. We use input coherent states of light to illustrate two variations of the method. However, we show that the scheme works equally well for arbitrary input fields and constitutes a universal procedure, which may thus prove a useful building block for quantum state engineering and quantum information processing with continuous-variable qubits.
authors.affiliation: Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy.
authors.forename: Antonio S
authors.initials: AS
authors.lastname: Coelho
authors.affiliation: Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy.|LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy.
authors.forename: Luca S
authors.initials: LS
authors.lastname: Costanzo
authors.affiliation: Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy.|LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zavatta
authors.affiliation: QOLS, The Blackett Laboratory, Imperial College London, SW7 2AZ, United Kingdom.
authors.forename: Catherine
authors.initials: C
authors.lastname: Hughes
authors.affiliation: QOLS, The Blackett Laboratory, Imperial College London, SW7 2AZ, United Kingdom.
authors.forename: M S
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Istituto Nazionale di Ottica (INO-CNR), Largo E. Fermi 6, 50125 Florence, Italy.|LENS and Department of Physics, University of Firenze, 50019 Sesto Fiorentino, Florence, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bellini