title: Polarization entangled state measurement on a chip.
abstract: The emerging strategy to overcome the limitations of bulk quantum optics consists of taking advantage of the robustness and compactness achievable by integrated waveguide technology. Here we report the realization of a directional coupler, fabricated by femtosecond laser waveguide writing, acting as an integrated beam splitter able to support polarization-encoded qubits. This maskless and single step technique allows us to realize circular transverse waveguide profiles which are able to support the propagation of gaussian modes with any polarization state. Using this device, we demonstrate quantum interference with polarization-entangled states and singlet state projection.
authors.affiliation: Dipartimento di Fisica, Sapienza Universitá di Roma, I-00185 Roma, Italy.
authors.forename: Linda
authors.initials: L
authors.lastname: Sansoni
authors.forename: Fabio
authors.initials: F
authors.lastname: Sciarrino
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vallone
authors.forename: Paolo
authors.initials: P
authors.lastname: Mataloni
authors.forename: Andrea
authors.initials: A
authors.lastname: Crespi
authors.forename: Roberta
authors.initials: R
authors.lastname: Ramponi
authors.forename: Roberto
authors.initials: R
authors.lastname: Osellame