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Motoya Shinozaki

Section

Advanced Institute for Materials Research

Job title

Specially Appointed Assistant Professor(Research)

Degree

博士（工学）（東北大学）
修士（工学）（東北大学）

researchmap

https://researchmap.jp/nanodora

J-GLOBAL ID

202201003638677024

e-Rad No.

50963998

ORCID

https://orcid.org/0000-0001-9460-9156

Research History 2

2025/05 - Present

National Institute for Materials Science　Research Center for Materials Nanoarchitectonics (MANA)　Visiting Researcher
2023/03 - Present

Advanced Institute for Materials Research (AIMR) , Tohoku University　Specially Appointed Assistant Professor

Education 3

東北大学大学院　工学研究科　電子工学専攻

2018/10 - 2022/03
東北大学大学院　工学研究科　電子工学専攻

2016/04 - 2018/03
Tohoku University　Faculty of Engineering

2014/04 - 2016/03

Committee Memberships 3

International Conference on Solid State Devices and Materials (SSDM)　Program Committee, Area 9

2025/01 - Present
東北大学附置研究所若手アンサンブルプロジェクト　ワーキンググループ委員

2024/09 - Present
日本物理学会　領域4 運営委員

2024/04 - 2025/03

Professional Memberships 1

The Physical Society of Japan

Research Interests 2

Quantum Device
Spintronics

Research Areas 3

Nanotechnology/Materials / Nanostructure physics /
Natural sciences / Semiconductors, optical and atomic physics /
Nanotechnology/Materials / Applied materials /

Awards 1

工学研究科長賞

2022/03　東北大学大学院工学研究科

Papers 16

RFSoC-based radio-frequency reflectometry in gate-defined bilayer graphene quantum devices Peer-reviewed

Motoya Shinozaki, Tomoya Johmen, Aruto Hosaka, Takumi Seo, Shunsuke Yashima, Akitomi Shirachi, Kosuke Noro, Shoichi Sato, Takeshi Kumasaka, Tsuyoshi Yoshida, Tomohiro Otsuka

Applied Physics Express　18　075001　2025/07/09
Publisher: IOP Publishing
DOI： 10.35848/1882-0786/ade6c2 　

ISSN： 1882-0778

eISSN： 1882-0786

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Abstract Quantum computers require scalability and high performance. While semiconductor quantum dots are promising candidates for qubits, the complexity of measurement setups poses a challenge for scaling up. Here, radio-frequency system-on-chip (RFSoC) technology is expected to be a promising approach. In this paper, we demonstrate RF reflectometry in gate-defined bilayer graphene quantum devices using RFSoC-based measurement architecture. By controlling the confinement strength, we achieve both Fabry-Pérot interferometer and quantum dot operations in a single device. We also identify pathways for sensitivity optimization through tunnel barrier engineering and resonator design. These results represent a step toward integrating high-bandwidth measurements with quantum devices.
Charge-state estimation in quantum dots using a Bayesian approach Peer-reviewed

Motoya Shinozaki, Yui Muto, Takahito Kitada, Tomohiro Otsuka

Physical Review Applied　23　(3)　034078　2025/03/26
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevapplied.23.034078 　

eISSN： 2331-7019
Dynamics of quantum cellular automata electron transition in triple quantum dots International-coauthorship Peer-reviewed

Takumi Aizawa, Motoya Shinozaki, Yoshihiro Fujiwara, Takeshi Kumasaka, Wataru Izumida, Arne Ludwig, Andreas D. Wieck, Tomohiro Otsuka

Physical Review B　110　235421　2024/12/18

DOI： 10.1103/PhysRevB.110.235421 　
Probing electron trapping by current collapse in GaN/AlGaN FETs utilizing quantum transport characteristics Peer-reviewed

Takaya Abe, Motoya Shinozaki, Kazuma Matsumura, Takumi Aizawa, Takeshi Kumasaka, Norikazu Ito, Taketoshi Tanaka, Ken Nakahara, Tomohiro Otsuka

Applied Physics Letters　125　253501　2024/12/16

DOI： 10.1063/5.0232463 　
Surface Gate-Defined Quantum Dots in MoS2 with Bi Contacts International-coauthorship Peer-reviewed

Riku Tataka, Alka Sharma, Motoya Shinozaki, Tomoya Johmen, Takeshi Kumasaka, Yong P. Chen, Tomohiro Otsuka

Journal of the Physical Society of Japan　93　094601　2024/09/15

DOI： 10.7566/JPSJ.93.094601 　
Microwave-dependent quantum transport characteristics in near pinched-off GaN/AlGaN field-effect transistors Peer-reviewed

Motoya Shinozaki, Takaya Abe, Kazuma Matsumura, Takumi Aizawa, Takeshi Kumasaka, Tomohiro Otsuka

Physical Review B　110　(3)　035305　2024/07/17
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevb.110.035305 　

ISSN： 2469-9950

eISSN： 2469-9969
Visual explanations of machine learning model estimating charge states in quantum dots International-coauthorship Peer-reviewed

Yui Muto, Takumi Nakaso, Motoya Shinozaki, Takumi Aizawa, Takahito Kitada, Takashi Nakajima, Matthieu R. Delbecq, Jun Yoneda, Kenta Takeda, Akito Noiri, Arne Ludwig, Andreas D. Wieck, Seigo Tarucha, Atsunori Kanemura, Motoki Shiga, Tomohiro Otsuka

APL Machine Learning　2　(2)　026110　2024/04/15
Publisher: AIP Publishing
DOI： 10.1063/5.0193621 　

eISSN： 2770-9019

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Charge state recognition in quantum dot devices is important in the preparation of quantum bits for quantum information processing. Toward auto-tuning of larger-scale quantum devices, automatic charge state recognition by machine learning has been demonstrated. For further development of this technology, an understanding of the operation of the machine learning model, which is usually a black box, will be useful. In this study, we analyze the explainability of the machine learning model estimating charge states in quantum dots by gradient weighted class activation mapping. This technique highlights the important regions in the image for predicting the class. The model predicts the state based on the change transition lines, indicating that human-like recognition is realized. We also demonstrate improvements of the model by utilizing feedback from the mapping results. Due to the simplicity of our simulation and pre-processing methods, our approach offers scalability without significant additional simulation costs, demonstrating its suitability for future quantum dot system expansions.
Wide dynamic range charge sensor operation by high-speed feedback control of radio-frequency reflectometry Peer-reviewed

Yoshihiro Fujiwara, Motoya Shinozaki, Kazuma Matsumura, Kosuke Noro, Riku Tataka, Shoichi Sato, Takeshi Kumasaka, Tomohiro Otsuka

Applied Physics Letters　123　(21)　213502　2023/11/20
Publisher: AIP Publishing
DOI： 10.1063/5.0167212 　

ISSN： 0003-6951

eISSN： 1077-3118

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Semiconductor quantum dots are useful for controlling and observing quantum states and can also be used as sensors for reading out quantum bits and exploring local electronic states in nanostructures. However, challenges remain for the sensor applications, such as the trade-off between sensitivity and dynamic range and the issue of instability due to external disturbances. In this study, we demonstrate proportional-integral-differential feedback control of the radio-frequency reflectometry in GaN nanodevices using a field-programmable gate array. This technique can maintain the operating point of the charge sensor with high sensitivity. The system also realizes a wide dynamic range and high sensor sensitivity through the monitoring of the feedback signal. This method has potential applications in exploring dynamics and instability of electronic and quantum states in nanostructures.
Radio-Frequency Reflectometry in Bilayer Graphene Devices Utilizing Microscale Graphite Back-Gates Peer-reviewed

Tomoya Johmen, Motoya Shinozaki, Yoshihiro Fujiwara, Takumi Aizawa, Tomohiro Otsuka

Physical Review Applied　20　(1)　014035　2023/07/17
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevapplied.20.014035 　

eISSN： 2331-7019
Nonlinear conductance in nanoscale CoFeB/MgO magnetic tunnel junctions with perpendicular easy axis International-coauthorship Peer-reviewed

Motoya Shinozaki, Junta Igarashi, Shuichi Iwakiri, Takahito Kitada, Keisuke Hayakawa, Butsurin Jinnai, Tomohiro Otsuka, Shunsuke Fukami, Kensuke Kobayashi, Hideo Ohno

Physical Review B　107　(9)　094436　2023/03/30

DOI： 10.1103/PhysRevB.107.094436 　

ISSN： 2469-9950

eISSN： 2469-9969
Scalable fabrication of graphene nanoribbon quantum dot devices with stable orbital-level spacing Peer-reviewed

Toshiaki Kato, Takahito Kitada, Mizuki Seo, Wakana Okita, Naofumi Sato, Motoya Shinozaki, Takaya Abe, Takeshi Kumasaka, Takumi Aizawa, Yui Muto, Toshiro Kaneko, Tomohiro Otsuka

Communications Materials　3　(1)　103　2022/12/22
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s43246-022-00326-3 　

ISSN： 2662-4443

eISSN： 2662-4443

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Abstract Large-scale integration of quantum-dot devices is essential for realizing various quantum devices. Graphene-based quantum dots provide a promising platform for spin qubits because of their low nuclear spin density and weak spin-orbit interaction. However, the integration of graphene-based quantum dots remains a challenge. Here, we demonstrate the scalable fabrication of graphene nanoribbon-based quantum-dot devices using a nickel nanobar technique. Fine structures formed in the middle of the nanoribbons exhibit quantum-dot behavior, and more than 56% of devices fabricated on the same substrate show Coulomb diamond features, indicating that large-scale integration of graphene nanoribbon quantum-dot devices is possible with our method. Cryogenic measurements reveal orbital-level spacings between the ground and excited states that are stable up to high-temperature conditions of ~20 K. We explain this stability in terms of the very fine structures formed in the middle of the nanoribbons and their relatively low effective mass.
Gate voltage dependence of noise distribution in radio-frequency reflectometry in gallium arsenide quantum dots International-coauthorship Peer-reviewed

Motoya Shinozaki, Yui Muto, Takahito Kitada, Takashi Nakajima, Matthieu R. Delbecq, Jun Yoneda, Kenta Takeda, Akito Noiri, Takumi Ito, Arne Ludwig, Andreas D. Wieck, Seigo Tarucha, Tomohiro Otsuka

Applied Physics Express　14　(3)　035002-035002　2021/03/01
Publisher: IOP Publishing
DOI： 10.35848/1882-0786/abe41f 　

ISSN： 1882-0778

eISSN： 1882-0786
Probing edge condition of nanoscale CoFeB/MgO magnetic tunnel junctions by spin-wave resonance Peer-reviewed

M. Shinozaki, T. Dohi, J. Igarashi, J. Llandro, S. Fukami, H. Sato, H. Ohno

Applied Physics Letters　117　(20)　202404-202404　2020/11/16
Publisher: {AIP} Publishing
DOI： 10.1063/5.0020591 　
Write-error rate of nanoscale magnetic tunnel junctions in the precessional regime Peer-reviewed

Takaharu Saino, Shun Kanai, Motoya Shinozaki, Butsurin Jinnai, Hideo Sato, Shunsuke Fukami, Hideo Ohno

Applied Physics Letters　115　(14)　142406-142406　2019/09/30
Publisher: {AIP} Publishing
DOI： 10.1063/1.5121157 　

ISSN： 0003-6951

eISSN： 1077-3118
Free-layer size dependence of anisotropy field in nanoscale CoFeB/MgO magnetic tunnel junctions Peer-reviewed

Motoya Shinozaki, Junta Igarashi, Hideo Sato, Hideo Ohno

Applied Physics Express　11　(4)　043001　2018

DOI： 10.7567/APEX.11.043001 　
Damping constant in a free layer in nanoscale CoFeB/MgO magnetic tunnel junctions investigated by homodyne-detected ferromagnetic resonance Peer-reviewed

Motoya Shinozaki, Eriko Hirayama, Shun Kanai, Hideo Sato, Fumihiro Matsukura, Hideo Ohno

Applied Physics Express　10　(1)　13001-13001　2017
Publisher: Institute of Physics
DOI： 10.7567/APEX.10.013001 　

ISSN： 1882-0778

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Research Projects 9

メタマテリアル構造によるグラフェン新奇物性発現・機能デバイス創出

篠﨑基矢

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 学術変革領域研究(A) 公募研究

Institution: 東北大学

2025/04 - 2027/03
超伝導体超薄膜による新原理トランジスタの創製

Offer Organization: 東北大学

System: はばたく若手支援事業

Institution: 東北大学

2025/07 - 2026/06
新原理トランジスタに向けた二次元超伝導体の電界制御に関する調査

岩切秀一, 篠﨑基矢

Offer Organization: 国立研究開発法人物質・材料研究機構, 東北大学

System: 2025 年度 TIA 連携プログラム探索推進事業「かけはし｣

Institution: 国立研究開発法人物質・材料研究機構, 東北大学

2025/06 - 2026/03
極低温動作高周波コンポーネント評価・活用による量子ビット読み出しのノイズ抑制・高速化

篠﨑基矢, 五十嵐純太

Offer Organization: 東北大学, 国立研究開発法人産業技術総合研究所

System: 東北大学-産総研マッチング研究支援事業

Institution: 東北大学, 国立研究開発法人産業技術総合研究所

2025/04 - 2026/03
二次元材料を用いたスピン軌道トルク磁気トンネル接合素子に関する研究

張超亮, 篠﨑基矢

Offer Organization: 公益財団法人ヒロセ財団

System: 研究助成

Institution: 東北大学

2023/11 - 2025/10
2次元材料におけるゲート誘起周期構造の開発

Offer Organization: 東北大学

System: 附置研究所若手研究者アンサンブルグラント

2024/06 - 2025/03
半導体量子ドットにおける超高速量子状態観測手法の開発実証

篠﨑基矢

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 研究活動スタート支援

Institution: 東京大学

2022/08 - 2024/03
磁性体スピントロニクスに基づく色中心エンジニアリング

篠﨑基矢

Offer Organization: 日本学術振興会

System: 科学研究費助成事業特別研究員奨励費

Category: 特別研究員奨励費

Institution: 東北大学

2020/04 - 2022/03

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半導体量子ドットは量子ビットとしての応用が期待される一方で、ナノスケールな局所電子状態のプロービングツールとしても有用である。今年度は半導体量子ドットを用いたミクロプローブ測定系の構築と改良、そして測定限界を決めるノイズメカニズムについて詳細に調べた。ミクロプローブは量子ドットを抵抗と見立てたRLC共振回路により主に構成され、計測対象の量子状態は量子ドットの抵抗変化を介して共振器から反射される高周波信号の振幅に反映される。この共振器の周波数特性や回路コンポーネントの影響が読み出し信号のノイズに反映されていることをモデル計算と実験から示した。また量子ドット中の電荷ゆらぎノイズとミクロプローブ感度との相関について詳細に調べた。得られた複数のノイズの周波数特性から、実際のミクロプローブによる実時間測定における主なノイズ源を積算時間の観点から整理し、ミクロプローブを用いた高速測定のノイズメカニズムの詳細を明らかにした。また、ノイズを低減して量子ドット中の電荷状態を調べるための信号処理手法として、これまでは時間積算による単純平均化が用いられてきた。この時間積算により状態読み出し速度が律されるため、これに代わる新たなアルゴリズムとしてベイズの定理を用いた状態推定手法を提案した。この手法により、従来の平均化手法よりもより高速に状態推定が可能であることを実証した。また、ノイズの低減には測定回路中のアンプの内因的ノイズを小さくすることが有効である。そこで低温で動作する低ノイズなパラメトリック増幅器を開発するなど、ハード・ソフトの両側面からノイズ低減に資する研究も遂行している。
スピントロニクスの量子情報研究への展開

Offer Organization: 東北大学学際高等研究教育院

System: 博士研究教育院生

2019/04 - 2022/03

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Teaching Experience 2

Experiments for Materials Engineering I　The University of Tokyo
Fundamentals of Materials Engineering and Exercise I　The University of Tokyo