title: Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser.
abstract: Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process, and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal, and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal, and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components, and will eventually realize scalable Q-ICT in optical infra-structures.
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Rui-Bo
authors.initials: RB
authors.lastname: Jin
authors.affiliation: University of Electro-Communications (UEC), 1-5-1 Chofugaoka, Chofu Tokyo 182-8585, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Shimizu
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Morohashi
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Wakui
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takeoka
authors.affiliation: 1] National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan [2] Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan.
authors.forename: Shuro
authors.initials: S
authors.lastname: Izumi
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Takahide
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Fujiwara
authors.affiliation: National Institute of Information and Communications Technology (NICT), 588-2 Iwaoka, Kobe 651-2492, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: National Institute of Information and Communications Technology (NICT), 588-2 Iwaoka, Kobe 651-2492, Japan.
authors.forename: Shigehito
authors.initials: S
authors.lastname: Miki
authors.affiliation: National Institute of Information and Communications Technology (NICT), 588-2 Iwaoka, Kobe 651-2492, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Terai
authors.affiliation: 1] National Institute of Information and Communications Technology (NICT), 588-2 Iwaoka, Kobe 651-2492, Japan [2] Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences (CAS), 865 Changning Road, Shanghai 200050, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: National Institute of Information and Communications Technology (NICT), 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Sasaki