title: Qutrit state engineering with biphotons.
abstract: The novel experimental realization of three-level optical quantum systems is presented. We use the polarization state of biphotons to generate a specific sequence of states that are used in the extended version of four-state QKD protocol quantum key distribution protocol. We experimentally verify the orthogonality of the basic states and demonstrate the ability to easily switch between them. The tomography procedure is employed to reconstruct the density matrices of generated states.
authors.affiliation: Russian Control System Agency, Angstrem, Moscow 124460 Russia.
authors.forename: Yu I
authors.initials: YI
authors.lastname: Bogdanov
authors.forename: M V
authors.initials: MV
authors.lastname: Chekhova
authors.forename: S P
authors.initials: SP
authors.lastname: Kulik
authors.forename: G A
authors.initials: GA
authors.lastname: Maslennikov
authors.forename: A A
authors.initials: AA
authors.lastname: Zhukov
authors.forename: C H
authors.initials: CH
authors.lastname: Oh
authors.forename: M K
authors.initials: MK
authors.lastname: Tey