title: Two-photon interference of temporally separated photons.
abstract: We present experimental demonstrations of two-photon interference involving temporally separated photons within two types of interferometers: a Mach-Zehnder interferometer and a polarization-based Michelson interferometer. The two-photon states are probabilistically prepared in a symmetrically superposed state within the two interferometer arms by introducing a large time delay between two input photons; this state is composed of two temporally separated photons, which are in two different or the same spatial modes. We then observe two-photon interference fringes involving both the Hong-Ou-Mandel interference effect and the interference of path-entangled two-photon states simultaneously in a single interferometric setup. The observed two-photon interference fringes provide simultaneous observation of the interferometric properties of the single-photon and two-photon wavepackets. The observations can also facilitate a more comprehensive understanding of the origins of the interference phenomena arising from spatially bunched/anti-bunched two-photon states comprised of two temporally separated photons within the interferometer arms.
authors.affiliation: Department of Physics, Pusan National University, Geumjeong-Gu, Busan 609-735, Korea.
authors.forename: Heonoh
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Physics, Pusan National University, Geumjeong-Gu, Busan 609-735, Korea.
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Physics, Pusan National University, Geumjeong-Gu, Busan 609-735, Korea.
authors.forename: Han Seb
authors.initials: HS
authors.lastname: Moon