Updated on 2022/06/30

写真a

 
KATO, Shinya
 
Affiliation
Affiliated organization, Waseda Institute for Advanced Study
Job title
Assistant Professor(without tenure)

Concurrent Post

  • Faculty of Science and Engineering   School of Advanced Science and Engineering

Education

  • 2008.04
    -
    2012.03

    Kyoto University   Graduate School of Science   Division of Physics and Astronomy  

  • 2006.04
    -
    2008.03

    Kyoto University   Graduate School of Science  

Degree

  • 京都大学   博士(理学)

Research Experience

  • 2020.04
    -
    Now

    Waseda Institute of Advanced Study   Assistant Professor

  • 2016.10
    -
    2020.03

    Japan Science and Technology Agency   PRESTO Researcher

  • 2014.04
    -
    2016.09

    JSPS Research Fellow (SPD)

  • 2012.04
    -
    2014.03

    Waseda University   Department of Applied Physics   Junior Researcher

  • 2008.04
    -
    2011.03

    日本学術振興会特別研究員(DC1)

 

Research Areas

  • Semiconductors, optical properties of condensed matter and atomic physics

Papers

  • Photon transport enhancement through a coupled-cavity QED system with dynamic modulation

    Shinya Kato, Takao Aoki

    Optics Express   30 ( 5 ) 6798 - 6798  2022.02  [Refereed]

    Authorship:Lead author, Corresponding author

    DOI

  • Ultra-low-loss nanofiber Fabry–Perot cavities optimized for cavity quantum electrodynamics

    S. K. Ruddell, K. E. Webb, M. Takahata, S. Kato, T. Aoki

    Optics Letters   45 ( 17 ) 4875 - 4875  2020.09  [Refereed]

    DOI

  • Transfer-Matrix Approach to Determining the Linear Response of All-Fiber Networks of Cavity-QED Systems

    Nikolett Német, Donald White, Shinya Kato, Scott Parkins, Takao Aoki

    Physical Review Applied   13 ( 6 )  2020.06  [Refereed]

    DOI

  • Cavity Dark Mode of Distant Coupled Atom-Cavity Systems

    Donald H. White, Shinya Kato, Nikolett Nemet, Scott Parkins, Takao Aoki

    PHYSICAL REVIEW LETTERS   122 ( 25 ) 253603 - 253603  2019.06  [Refereed]  [International journal]

     View Summary

    We report on a combined experimental and theoretical investigation into the normal modes of an all-fiber coupled cavity-quantum-electrodynamics system. The interaction between atomic ensembles and photons in the same cavities, and that between the photons in these cavities and the photons in the fiber connecting these cavities, generates five nondegenerate normal modes. We demonstrate our ability to excite each normal mode individually. We study particularly the "cavity dark mode," in which the two cavities coupled directly to the atoms do not exhibit photonic excitation. Through the observation of this mode, we demonstrate remote excitation and nonlocal saturation of atoms.

    DOI PubMed

  • Observation of dressed states of distant atoms with delocalized photons in coupled-cavities quantum electrodynamics

    Shinya Kato, Nikolett Nemet, Kohei Senga, Shota Mizukami, Xinhe Huang, Scott Parkins, Takao Aoki

    NATURE COMMUNICATIONS   10 ( 1 ) 1160 - 1160  2019.03  [Refereed]  [International journal]

    Authorship:Lead author

     View Summary

    In a cavity quantum electrodynamics (QED) system, where atoms coherently interact with photons in a cavity, the eigenstates of the system are the superposition states of atoms and cavity photons, the so-called dressed states of atoms. When two cavities are connected by an optical fiber with negligible loss, the coherent coupling between the cavities gives rise to photonic normal modes. One of these normal modes is the fiber-dark mode, in which photons are delocalized in the two distant cavities. Here we demonstrate the setting of coupled-cavities QED, where two nanofiber cavity-QED systems are coherently connected by a meter-long low-loss channel in an all-fiber fashion. Specifically, we observe dressed states of distant atoms with delocalized photons of the fiber-dark normal mode. Our system will provide a platform for the study of delocalized atomic and photonic states, photonic many-body physics, and distributed quantum computation.

    DOI PubMed

  • Laser spectroscopic probing of coexisting superfluid and insulating states of an atomic Bose-Hubbard system

    Shinya Kato, Kensuke Inaba, Seiji Sugawa, Kosuke Shibata, Ryuta Yamamoto, Makoto Yamashita, Yoshiro Takahashi

    NATURE COMMUNICATIONS   7   11341 - 11341  2016.04  [Refereed]  [International journal]

    Authorship:Lead author

     View Summary

    A system of ultracold atoms in an optical lattice has been regarded as an ideal quantum simulator for a Hubbard model with extremely high controllability of the system parameters. While making use of the controllability, a comprehensive measurement across the weakly to strongly interacting regimes in the Hubbard model to discuss the quantum many-body state is still limited. Here we observe a great change in the excitation energy spectra across the two regimes in an atomic Bose-Hubbard system by using a spectroscopic technique, which can resolve the site occupancy in the lattice. By quantitatively comparing the observed spectra and numerical simulations based on sum rule relations and a binary fluid treatment under a finite temperature Gutzwiller approximation, we show that the spectra reflect the coexistence of a delocalized superfluid state and a localized insulating state across the two regimes.

    DOI PubMed

  • Strong Coupling between a Trapped Single Atom and an All-Fiber Cavity

    Shinya Kato, Takao Aoki

    PHYSICAL REVIEW LETTERS   115 ( 9 ) 093603 - 093603  2015.08  [Refereed]  [International journal]

    Authorship:Lead author

     View Summary

    We demonstrate an all-fiber cavity quantum electrodynamics system with a trapped single atom in the strong coupling regime. We use a nanofiber Fabry-Perot cavity, that is, an optical nanofiber sandwiched by two fiber-Bragg-grating mirrors. Measurements of the cavity transmission spectrum with a single atom in a state-insensitive nanofiber trap clearly reveal the vacuum Rabi splitting.

    DOI PubMed

  • Efficient Single-Mode Photon-Coupling Device Utilizing a Nanofiber Tip

    Sho Chonan, Shinya Kato, Takao Aoki

    SCIENTIFIC REPORTS   4   4785 - 4785  2014.04  [Refereed]  [International journal]

     View Summary

    Single-photon sources are important elements in quantum optics and quantum information science. It is crucial that such sources be able to couple photons emitted from a single quantum emitter to a single propagating mode, preferably to the guided mode of a single-mode optical fiber, with high efficiency. Various photonic devices have been successfully demonstrated to efficiently couple photons from an emitter to a single mode of a cavity or a waveguide. However, efficient coupling of these devices to optical fibers is sometimes challenging. Here we show that up to 38% of photons from an emitter can be directly coupled to a single-mode optical fiber by utilizing the flat tip of a silica nanofiber. With the aid of a metallic mirror, the efficiency can be increased to 76%. The use of a silicon waveguide further increases the efficiency to 87%. This simple device can be applied to various quantum emitters.

    DOI PubMed

  • High-numerical-aperture microlensed tip on an air-clad optical fiber

    Shinya Kato, Sho Chonan, Takao Aoki

    OPTICS LETTERS   39 ( 4 ) 773 - 776  2014.02  [Refereed]  [International journal]

    Authorship:Lead author

     View Summary

    We show that a hemispherically shaped tip on an air-clad optical fiber simultaneously works as a high-numerical-aperture lens and efficiently collects photons from an emitter placed near the beam waist into the fundamental guided mode. Numerical simulations show that the coupling efficiency reaches about 25%. We have constructed a confocal microscope with such a lensed fiber. The measurements are in good agreement with the numerical simulation. The monolithic structure with a high-photon-collection efficiency will provide a flexible substitute for a conventional lens system in various experiments such as single-atom trapping with a tightly focused optical trap. (C) 2014 Optical Society of America

    DOI PubMed

  • Strongly interacting array of Bose-Einstein condensates trapped in a one-dimensional optical lattice

    Makoto Yamashita, Shinya Kato, Atsushi Yamaguchi, Seiji Sugawa, Takeshi Fukuhara, Satoshi Uetake, Yoshiro Takahashi

    PHYSICAL REVIEW A   87 ( 4 )  2013.04  [Refereed]

     View Summary

    We study a strongly interacting array of Bose-Einstein condensates trapped in a one-dimensional (1D) optical lattice. The system is described by a nonstandard 1D Bose-Hubbard model in which both the tunneling matrix element and the on-site atomic interaction depend on the lattice site due to the interaction broadening of the local wave function and the system inhomogeneity. We quantitatively compare theoretical analyses based on the Gutzwiller approximation with experimental observations obtained using ytterbium atoms. We show that atomic states are highly number squeezed owing to strong interatomic interactions as the lattice potential becomes deeper. Furthermore, the calculated inhomogeneous collisional broadening of spectroscopic line shapes agrees well with high-resolution spectra measured by using the ultranarrow magnetic quadrupole S-1(0)-P-3(2) transition.

    DOI

  • Control of Resonant Interaction between Electronic Ground and Excited States

    Shinya Kato, Seiji Sugawa, Kosuke Shibata, Ryuta Yamamoto, Yoshiro Takahashi

    PHYSICAL REVIEW LETTERS   110 ( 17 ) 173201 - 173201  2013.04  [Refereed]  [International journal]

    Authorship:Lead author

     View Summary

    We observe magnetic Feshbach resonances in a collision between the ground and metastable states of two-electron atoms of ytterbium (Yb). We measure the on-site interaction of doubly occupied sites of an atomic Mott-insulator state in a three-dimensional optical lattice as a collisional frequency shift in a high-resolution laser spectroscopy. The observed spectra are well fitted by a simple theoretical formula, in which two particles with an s-wave contact interaction are confined in a harmonic trap. This analysis reveals a wide variation of the interaction with a resonance behavior around a magnetic field of about 1.1 G for the energetically lowest magnetic sublevel of Yb-170, as well as around 360 mG for the energetically highest magnetic sublevel of Yb-174. The observed Feshbach resonance can only be induced by an anisotropic interatomic interaction. This scheme will open the door to a variety of studies using two-electron atoms with tunable interaction. DOI: 10.1103/PhysRevLett.110.173201

    DOI PubMed

  • Highly Efficient Light Collecting Devices Utilizing a Nanofiber Tip

    Sho Chonan, Shinya Kato, Takao Aoki

    2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS PACIFIC RIM (CLEO-PR)    2013  [Refereed]

     View Summary

    We have performed numerical simulations of light collecting devices utilizing a silica nanofiber tip. Up to 39% of light from a point dipole source can be coupled to the fundamental guided mode of the nanofiber.

  • Observation of long-lived van derWaals molecules in an optical lattice

    Shinya Kato, Rekishu Yamazaki, Kosuke Shibata, Ryuta Yamamoto, Hirotaka Yamada, Yoshiro Takahashi

    PHYSICAL REVIEW A   86 ( 4 )  2012.10  [Refereed]

    Authorship:Lead author

     View Summary

    We observe long-lived tightly bound van der Waals molecules of ytterbium in a three-dimensional optical lattice with a lifetime of 8.0 s. The molecules, state-selectively produced by a photoassociation technique from a Bose-Einstein condensate or an atomic Mott insulator, are successfully detected with a photodissociation method where the molecules are photodissociated into two atoms and the atoms are captured by a magneto-optical trap or optical molasses, for the fluorescence detection. This work will open up various possibilities of research with van der Waals molecules in an optical lattice.

    DOI

  • Optical magnetic resonance imaging with an ultra-narrow optical transition

    S. Kato, K. Shibata, R. Yamamoto, Y. Yoshikawa, Y. Takahashi

    Applied Physics B: Lasers and Optics   108 ( 1 ) 31 - 38  2012.07  [Refereed]

    Authorship:Lead author

     View Summary

    We demonstrate optical magnetic resonance imaging (OMRI) of a Bose-Einstein condensate of ytterbium atoms trapped in a one-dimensional (1D) optical lattice using an ultra-narrow optical transition 1S 0↔ 3P 2 (m=-2). We developed a vacuum chamber equipped with a thin glass cell, which provides high optical access and allows a compact design of magnetic coils. A line shape of a measured spectrum of the OMRI is well described by a spatial distribution of the atoms in a 1D optical lattice with the Thomas-Fermi approximation and an applied magnetic field gradient. The observed spectrum exhibits a periodic structure corresponding to the optical lattice periodicity. © 2012 Springer-Verlag.

    DOI

  • High-resolution laser spectroscopy of a Bose-Einstein condensate using the ultranarrow magnetic quadrupole transition

    A. Yamaguchi, S. Uetake, S. Kato, H. Ito, Y. Takahashi

    NEW JOURNAL OF PHYSICS   12  2010.10  [Refereed]

     View Summary

    High-resolution laser spectroscopy of a Bose-Einstein condensate (BEC) was performed by using the ultranarrow magnetic quadrupole (6s(2)) (1)S(0) <-> (6s6p) (3)P(2) transition of ytterbium (Yb). The transition from the Doppler-broadened spectrum of thermal atoms to the asymmetric spectrum, reflecting the inhomogeneous density distribution of a BEC in a harmonic trap, was observed. The role of the inter-atomic interaction was highlighted by performing spectroscopy of a BEC loaded in a one-dimensional (1D) optical lattice.

    DOI

  • A scalable quantum computer with ultranarrow optical transition of ultracold neutral atoms in an optical lattice

    K. Shibata, S. Kato, A. Yamaguchi, S. Uetake, Y. Takahashi

    APPLIED PHYSICS B-LASERS AND OPTICS   97 ( 4 ) 753 - 758  2009.12  [Refereed]

     View Summary

    We propose a new quantum-computing scheme using ultracold neutral ytterbium atoms in an optical lattice, especially in a monolayer of three-dimensional optical lattice. The nuclear Zeeman sublevels define a qubit. This choice avoids the natural phase evolution due to the magnetic dipole interaction between qubits. The Zeeman sublevels with large magnetic moments in the long-lived metastable state are also exploited to address individual atoms and to construct a controlled-multiqubit gate. Estimated parameters required for this scheme show that this proposal is scalable and experimentally feasible.

    DOI

  • QUANTUM DEGENERATE GASES OF YTTERBIUM ATOMS

    S. Uetake, A. Yamaguchi, S. Kato, T. Fukuhara, S. Sugawa, K. Enomoto, Y. Takasu, Y. Takahashi

    PROCEEDINGS OF THE 9TH INTERNATIONAL SYMPOSIUM ON FOUNDATIONS OF QUANTUM MECHANICS IN THE LIGHT OF NEW TECHNOLOGY     12 - +  2009  [Refereed]

     View Summary

    We have performed high-resolution spectroscopy of quantum degenerate gases of bosonic and fermionic ytterbium atoms using ultra-narrow intercombination transitions to probe quantum properties of the gases. The mean field interaction of the Bose-Einstein condensation and the energy distribution characteristic of the Fermi degeneracy were observed in the spectra.

  • High power narrow linewidth laser at 556 nm for magneto-optical trapping of ytterbium

    S. Uetake, A. Yamaguchi, S. Kato, Y. Takahashi

    APPLIED PHYSICS B-LASERS AND OPTICS   92 ( 1 ) 33 - 35  2008.07  [Refereed]

     View Summary

    We present a high-power and narrow-linewidth laser for intercombination magneto-optical trapping of ytterbium (Yb) atoms using the 6s(2) S-1(0)-6s6p P-3(1) transition. The system generates 415 mW of continuous wave laser radiation at 556 nm with a linewidth of less than 100 kHz. It is based on a commercial 1W fiber laser with a frequency doubling stage. Up to 58% frequency doubling efficiency is obtained at an input power of 0.5W by using a lithium triborate crystal as a nonlinear medium. The system has been successfully used for laser cooling of Yb atoms.

    DOI

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Misc

  • 21pAL-6 Development of quantum gas microscope of ytterbium atoms 1

    Shibata Kosuke, Yamamoto Ryuta, Kato Shinya, Takahashi Yoshiro

    Meeting abstracts of the Physical Society of Japan   67 ( 2 ) 180 - 180  2012.08

    CiNii

  • 21pAL-9 Control of a scattering length of Ytterbium atoms through anisotropic interaction

    Kato S., Sugawa S., Shibata K., Yamamoto R., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   67 ( 2 ) 181 - 181  2012.08

    CiNii

  • 18pAL-8 Few-body effects on spectra of Yb atoms in an optical lattice

    Inaba K., Yamashita M., Kato S., Shibata K., Yamamoto R., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   67 ( 2 ) 135 - 135  2012.08

    CiNii

  • 25aBE-9 Spectroscopy of ultracold ^<174>Yb atoms in a three dimensional optical lattice

    Inaba K., Yamashita M., Kato S., Shibata K., Yamamoto R., Yoshikawa Y., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   67 ( 1 ) 203 - 203  2012.03

    CiNii

  • 30pSD-8 Optical lattice experiments of quantum degenerate ytterbium atoms IV

    Fukuhara Takeshi, Uetake Satoshi, Kakiuchi Hisashi, Sugawa Seiji, Sugimoto Masahito, Taie Shintaro, Kato Shinya, Takahashi Yoshiro

    Meeting abstracts of the Physical Society of Japan   64 ( 1 ) 187 - 187  2009.03

    CiNii

  • 25pQD-13 High-resolution spectroscopy of ultracold ytterbium atoms using the ^1S_0-^3P_2 transition

    Yamaguchi A., Uetake S., Kato S., Ito H., Takasu Y., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   63 ( 1 ) 188 - 188  2008.02

    CiNii

  • 19pXK-4 High-resolution spectroscopy of ^1S_0-^3P_0 transition in ultra-cold Yb atoms

    Uetake S., Yamaguchi A., Kato S., Li Y., Hosokawa M., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   62 ( 1 ) 150 - 150  2007.02

    CiNii

  • 19pXK-5 Direct excitation of cold Yb atoms to the ^3P_2 state I

    Yamaguchi A., Uetake S., Kato S., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   62 ( 1 ) 151 - 151  2007.02

    CiNii

  • 24aRB-8 Collisional properties of cold Yb atoms in the ^3P_2 state

    Yamaguchi A., Uetake S., Hashimoto D., Kato S., Takahashi Y.

    Meeting abstracts of the Physical Society of Japan   61 ( 2 ) 95 - 95  2006.08

    CiNii

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Presentations

  • ナノ光ファイバー共振器量子電気力学系

    加藤真也  [Invited]

    システムナノ技術に関する特別研究専門委員会第2回研究会 

    Presentation date: 2021.06

  • 量子マイクロ波フォトニクスに向けた量子トランスデューサ

    山口祐也, 菅野敦史, 山本直克, 山崎歴舟, 加藤真也, 青木隆朗, 野口篤史, 佐々木 遼, 不破麻里亜, 宇佐見康二, 中村泰信  [Invited]

    電子情報通信学会マイクロ波フォトニクス研究会 

    Presentation date: 2021.05

  • 量子マイクロ波フォトニクスに向けた薄膜LNデバイス

    山口祐也, 菅野敦史, 山本直克, 山崎歴舟, 加藤真也, 野口篤史, 宇都隆宏, 加納正太郎, 佐々木遼, 不破麻里亜, 宇佐見康二, 中村泰信

    2021年電子情報通信学会総合大会 

    Presentation date: 2021.03

Specific Research

  • 高性能ファイバーブラッグミラーの開発とそれを用いた光学実験

    2021   青木隆朗

     View Summary

    光ファイバー共振器はファイバーレーザーへの応用や、センシング技術、また、量子光学実験への適用など、幅広い光学実験で活用される重要なデバイスである。本研究では光ファイバー内に埋め込まれたブラッグミラーを作製する装置を開発し、低損失なブラッグミラーを光ファイバー上で高い位置制御性を持って作製することに成功した。この装置を利用して、通常は数十メートル程度の長さのファイバーリング共振器を用いて作られるブリルアン散乱レーザーを共振器長さ5 mmのFabry-Perot型ファイバー共振器で実現した。高い共振器性能から発振閾値は1 mWを下回り、一般の光共振器を用いた場合によくみられるカスケード発振を防ぐことにも成功した。

  • 量子状態制御可能な単一原子トラップシステム実現に向けた装置開発

    2020   青木隆朗

     View Summary

    本課題の目標である量子状態制御可能な単一原子トラップシステムに向けて、特殊光トラップの設計および量子状態制御に活用する高性能光共振器の開発を行った。光トラップ設計は数値シミュレーションを基礎に必要なレーザーの強度やビーム形状についての考察を行った。また、具体的に装置として作製するために必要な光学素子の選定や性能評価を行った。光共振器開発は原子トラップにも必要となる光ファイバーの追加工の精度を大幅に向上させた。一連の結果については投稿論文としてまとめた。また、光共振器のミラーの作製技術も大幅に改善し光共振器の性能の大幅向上にも成功した。

 

Syllabus

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