title: Synchronization of optical photons for quantum information processing.
abstract: A fundamental element of quantum information processing with photonic qubits is the nonclassical quantum interference between two photons when they bunch together via the Hong-Ou-Mandel (HOM) effect. Ultimately, many such photons must be processed in complex interferometric networks. For this purpose, it is essential to synchronize the arrival times of the flying photons and to keep their purities high. On the basis of the recent experimental success of single-photon storage with high purity, we demonstrate for the first time the HOM interference of two heralded, nearly pure optical photons synchronized through two independent quantum memories. Controlled storage times of up to 1.8 μs for about 90 events per second were achieved with purities that were sufficiently high for a negative Wigner function confirmed with homodyne measurements.
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Makino
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Hashimoto
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Jun-Ichi
authors.identifier: 0000-0001-5344-4949
authors.initials: J
authors.lastname: Yoshikawa
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Ohdan
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Toyama
authors.affiliation: Institute of Physics, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55099 Mainz, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: van Loock
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Akira
authors.identifier: 0000-0002-6176-6742
authors.initials: A
authors.lastname: Furusawa
mesh_terms: D006801:Humans; D008962:Models, Theoretical; D017785:Photons; D011789:Quantum Theory
keywords: Hong-Ou-Mandel effect; Quantum information processing; Wigner function; concatenated cavity; homodyne measurement; parametric down conversion; quantum memory; quantum optics; quantum state tomography; single photon