title: Stabilization of a long-armed fiber-optic single-photon interferometer.
abstract: We report on single-photon interference experiments in a Michelson-type interferometer built with two 6-km-long fiber spools, as well as on the active stabilization of the interferometer. A weak coherent light signal was (de-) multiplexed with a strong reference light using wavelength-division multiplexing technique, and real-time feedback control technique was applied for the reference light to actively stabilize the phase fluctuation in the long-armed fiber interferometer. The stabilized interferometer showed phase stability of 0.06 rad, which corresponds to an optical path length fluctuation of 15 nm between the 6-km-long interfering arms. The raw visibility obtained without subtracting noise counts in the single-photon interference experiment was more than 98% for stabilized conditions.
authors.affiliation: Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea.
authors.forename: Seok-Beom
authors.initials: SB
authors.lastname: Cho
authors.forename: Tae-Gon
authors.initials: TG
authors.lastname: Noh