碁盤 晃久 (ゴバン アキヒサ)

写真a

所属

理工学術院 理工学術院総合研究所

職名

次席研究員(研究院講師)

経歴 【 表示 / 非表示

  • 2015年10月
    -
    継続中

    コロラド大学ボルダー校   JILA   ポスドク

  • 2015年07月
    -
    2015年09月

    カリフォルニア工科大学   ポスドク

 

研究分野 【 表示 / 非表示

  • 半導体、光物性、原子物理

論文 【 表示 / 非表示

  • On-chip photon-pair generation in a silica microtoroidal cavity

    Yosuke Hashimoto, Akihisa Goban, Yuki Hirabayashi, Yuta Kobayashi, Tomohiro Araki, Takao Aoki

    OPTICS EXPRESS   29 ( 3 ) 3533 - 3542  2021年02月

     概要を見る

    Microcavities with high Q factor and small mode volume have the potential to be efficient and compact sources of photon pairs. Here, we demonstrate on-chip photonpair generation by spontaneous tour-wave mixing in a silica microtoroidal cavity and obtain a coincidence-to-accidental ratio of 7.4 +/- 0.1 with a pump power of 46 mu W. The heralded photons also exhibit antibunching characterized by autocorrelation function values of g(c)(()(2)) (0) = 0.57 +/- 0.03<1. Comparing with a scaling model, the main noise source is found to be spontaneous Raman scattering in the cavity. This work opens a new possible means fur realizing integrated nonclassical photon sources based on silica photonic circuits toward scalable quantum technologies. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

    DOI

  • Thermodynamics of a deeply degenerate SU(N)-symmetric Fermi gas

    Lindsay Sonderhouse, Christian Sanner, Ross B. Hutson, Akihisa Goban, Thomas Bilitewski, Lingfeng Yan, William R. Milner, Ana M. Rey, Jun Ye

    NATURE PHYSICS   16 ( 12 )  2020年12月

     概要を見る

    Many-body quantum systems can exhibit a striking degree of symmetry unparallelled in their classical counterparts. In real materials SU(N) symmetry is an idealization, but this symmetry is pristinely realized in fully controllable ultracold alkaline-earth atomic gases. Here, we study an SU(N)-symmetric Fermi liquid of(87)Sr atoms, whereNcan be tuned to be as large as 10. In the deeply degenerate regime, we show through precise measurements of density fluctuations and expansion dynamics that the largeNof spin states under SU(N) symmetry leads to pronounced interaction effects in a system with a nominally negligible interaction parameter. Accounting for these effects, we demonstrate thermometry accurate to 1% of the Fermi energy. We also demonstrate record speed for preparing degenerate Fermi seas enabled by the SU(N)-symmetric interactions, reachingT/T-F = 0.22 with 10 nuclear spin states in 0.6 s working with a laser-cooled sample. This, along with the introduction of a new spin polarizing method, enables the operation of a three-dimensional optical lattice clock in the band insulating regime.Ultracold alkaline-earth fermionic atoms with large number of nuclear spin states possess SU(N) symmetry. That deeply affects their interaction properties, and allows a Fermi gas of these atoms to be cooled quickly to the quantum degenerate regime.

    DOI

  • Demonstration of 4.8 x10(-17) stability at 1s for two independent optical clocks

    E. Oelker, R. B. Hutson, C. J. Kennedy, L. Sonderhouse, T. Bothwell, A. Goban, D. Kedar, C. Sanner, J. M. Robinson, G. E. Marti, D. G. Matei, T. Legero, M. Giunta, R. Holzwarth, F. Riehle, U. Sterr, J. Ye

    NATURE PHOTONICS   13 ( 10 ) 714 - +  2019年10月

     概要を見る

    Optical atomic clocks require local oscillators with exceptional optical coherence owing to the challenge of performing spectros-copy on their ultranarrow-linewidth clock transitions. Advances in laser stabilization have thus enabled rapid progress in clock precision. A new class of ultrastable lasers based on cryogenic silicon reference cavities has recently demonstrated the longest optical coherence times to date. Here we utilize such a local oscillator with two strontium (Sr) optical lattice clocks to achieve an advance in clock stability. Through an anti-synchronous comparison, the fractional instability of both clocks is assessed to be 4.8 x 10(-17) / root tau for an averaging time tau (in seconds). Synchronous interrogation enables each clock to average at a rate of 3.5 x 10(-17) / root tau, dominated by quantum projection noise, and reach an instability of 6.6 x 10(-19) over an hour-long measurement. The ability to resolve sub-10(-18)-level frequency shifts in such short timescales will affect a wide range of applications for clocks in quantum sensing and fundamental physics.

    DOI

  • Engineering Quantum States of Matter for Atomic Clocks in Shallow Optical Lattices

    Ross B. Hutson, Akihisa Goban, G. Edward Marti, Lindsay Sonderhouse, Christian Sanner, Jun Ye

    PHYSICAL REVIEW LETTERS   123 ( 12 )  2019年09月

     概要を見る

    We investigate the effects of stimulated scattering of optical lattice photons on atomic coherence times in a state-of-the art Sr-87 optical lattice clock. Such scattering processes are found to limit the achievable coherence times to less than 12 s (corresponding to a quality factor of 1 x 10(16)), significantly shorter than the predicted 145(40) s lifetime of Sr-87's excited clock state. We suggest that shallow, state-independent optical lattices with increased lattice constants can give rise to sufficiently small lattice photon scattering and motional dephasing rates as to enable coherence times on the order of the clock transition's natural lifetime. Not only should this scheme be compatible with the relatively high atomic density associated with Fermi-degenerate gases in three-dimensional optical lattices, but we anticipate that certain properties of various quantum states of matter-such as the localization of atoms in a Mott insulator-can be used to suppress dephasing due to tunneling.

    DOI

  • Emergence of multi-body interactions in a fermionic lattice clock

    Goban A, Hutson R. B, Marti G. E, Campbell S. L, Perlin M. A, Julienne P. S, D'Incao J. P, Rey A. M, Ye J

    NATURE   563 ( 7731 ) 369 - +  2018年11月  [査読有り]

    DOI

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