title: Homodyne tomography characterization and nonlocality of a dual-mode optical qubit.
abstract: A single photon, delocalized over two optical modes, is characterized by means of quantum homodyne tomography. The reconstructed four-dimensional density matrix extends over the entire Hilbert space and thus reveals, for the first time, complete information about the dual-rail optical quantum bit as a state of the electromagnetic field. The experimental data violate the Bell inequality albeit with a loophole similar to the detection loophole in photon counting experiments.
authors.affiliation: Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
authors.forename: S A
authors.initials: SA
authors.lastname: Babichev
authors.forename: J
authors.initials: J
authors.lastname: Appel
authors.forename: A I
authors.initials: AI
authors.lastname: Lvovsky