Seki, Yuya

写真a

Affiliation

Graduate School of Science and Technology (Yagami)

Position

Project Senior Assistant Professor (Non-tenured)/Project Assistant Professor (Non-tenured)/Project Lecturer (Non-tenured)
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Career 【 Display / hide 】

  • 2016.04
    -
    2018.04

    Tohoku University, Graduate School of Information Sciences, Project Assistant Professor

  • 2018.05
    -
    2021.05

    National Institute of Advanced Industrial Science and Technology, Research Center for Emerging Computing Technologies, 産総研特別研究員

  • 2021.06
    -
    Present

    Keio University, Graduate School of Science and Technology, Project Lecturer

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Academic Background 【 Display / hide 】

  • 2007.04
    -
    2011.03

    Tokyo Institute of Technology, School of Science, Department of Physics

    University, Graduated

  • 2011.04
    -
    2013.03

    Tokyo Institute of Technology, Graduate School of Science and Engineering, Condensed Matter Physics

    Graduate School, Completed, Master's course

  • 2013.04
    -
    2016.03

    Tokyo Institute of Technology, Graduate School of Science and Engineering, Condensed Matter Physics

    Graduate School, Completed, Doctoral course

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Research Areas 【 Display / hide 】

  • Natural Science / Mathematical physics and fundamental theory of condensed matter physics

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Books 【 Display / hide 】

  • 量子技術の実用化と研究開発業務への導入方法

    関優也, 技術情報協会, 2023.01,  Page： 484p

    Scope: 第3節 Non-stoquastic 演算子による量子アニーリングの高速化 ～性能向上と応用の拡大～

  • 量子技術の実用化と研究開発業務への導入方法

    田中宗, 関優也, 技術情報協会, 2023.01,  Page： 484p

    Scope: 第2節 量子アニーリング等イジングマシン分野の研究開発

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Papers 【 Display / hide 】

  • Towards optimization of photonic-crystal surface-emitting lasers via quantum annealing

    Takuya Inoue, Yuya Seki, Shu Tanaka, Nozomu Togawa, Kenji Ishizaki, Susumu Noda

    Optics Express (Optica Publishing Group)  30 ( 24 ) 43503 - 43512 2022.11

    Accepted,  ISSN  1094-4087

    　View Summary

    <jats:p>Photonic-crystal surface-emitting lasers (PCSELs), which utilize a two-dimensional (2D) optical resonance inside a photonic crystal for lasing, feature various outstanding functionalities such as single-mode high-power operation and arbitrary control of beam polarizations. Although most of the previous designs of PCSELs employ spatially uniform photonic crystals, it is expected that lasing performance can be further improved if it becomes possible to optimize the spatial distribution of photonic crystals. In this paper, we investigate the structural optimization of PCSELs via quantum annealing towards high-power, narrow-beam-divergence operation with linear polarization. The optimization of PCSELs is performed by the iteration of the following three steps: (1) time-dependent 3D coupled-wave analysis of lasing performance, (2) formulation of the lasing performance via a factorization machine, and (3) selection of optimal solution(s) via quantum annealing. By using this approach, we discover an advanced PCSEL with a non-uniform spatial distribution of the band-edge frequency and injection current, which simultaneously enables higher output power, a narrower divergence angle, and a higher linear polarization ratio than conventional uniform PCSELs. Our results potentially indicate the universal applicability of quantum annealing, which has been mainly applied to specific types of discrete optimization problems so far, for various physics and engineering problems in the field of smart manufacturing.</jats:p>

  • Quantum annealing with twisted fields

    Takashi Imoto, Yuya Seki, Yuichiro Matsuzaki, Shiro Kawabata

    New Journal of Physics (IOP Publishing)  24 ( 11 ) 113009 - 113009 2022.11

    Accepted,  ISSN  13672630

    　View Summary

    Abstract

    Quantum annealing (QA) is a promising method for solving combinational optimization problems and performing quantum chemical calculations. The main sources of errors in QA are the effects of decoherence and non-adiabatic transition. We propose a method for suppressing both these effects using inhomogeneous twist operators corresponding to the twist angles of transverse fields applied to qubits. Furthermore, we adopt variational methods to determine the optimal inhomogeneous twist operator for minimizing the energy of the state after QA. Our approach is useful for increasing the energy gap and/or making the quantum states robust against decoherence during QA. In summary, our results can pave the way to a new approach for realizing practical QA.

  • Guaranteed-accuracy quantum annealing

    Takashi Imoto, Yuya Seki, Yuichiro Matsuzaki, Shiro Kawabata

    Physical Review A (American Physical Society (APS))  106 ( 4 )  2022.10

    Accepted,  ISSN  24699926

    　View Summary

    Quantum chemistry calculations constitute an important application of quantum annealing (QA). For practical applications in quantum chemistry, it is essential to estimate the ground-state energy of the Hamiltonian with chemical accuracy. However, there is no known method for guaranteeing the accuracy of the energy estimated via QA. Here, we propose a method for guaranteeing the accuracy of the energy estimated via QA using the Weinstein and Temple bounds. In our scheme, before QA is performed, the energies of the ground state and first excited state must be preestimated with some error bars (corresponding to the possible estimation error) via classical computation with some approximations. We show that, if the expectation value and standard deviation of the energy of the state after QA are lower than certain threshold values (that we can calculate from the preestimation), the ground-state energy estimated by QA is closer to the ground-state energy than the preestimation. As the expectation value and standard deviation of the energy can be experimentally measured via QA, our results pave the way for accurate estimation of the ground-state energy using QA.

  • Obtaining Ground States of the XXZ Model Using the Quantum Annealing with Inductively Coupled Superconducting Flux Qubits

    Takashi Imoto, Yuya Seki, Yuichiro Matsuzaki

    Journal of the Physical Society of Japan (Physical Society of Japan)  91 ( 6 )  2022.06

    Accepted,  ISSN  00319015

    　View Summary

    Obtaining ground states of Hamiltonians is important in the condensed matter physics and the quantum chemistry. The interaction Hamiltonians typically contain not only diagonal but also off-diagonal elements. Although quantum annealing provides a way to obtain a ground state of a Hamiltonian, we can only use the Hamiltonian with Ising interaction by using currently available commercial quantum annealing devices. In this work, we propose a quantum annealing for the XXZ model, which contains both Ising interaction and energy-exchange interaction, by using inductively coupled superconducting flux qubits. The key idea is to use a recently proposed spin-lock quantum annealing where the qubits are driven by microwave fields. As long as the rotating wave approximation is valid, the inductive coupling between the superconducting flux qubits produces the desired Hamiltonian in the rotating frame, and we can use such an interaction for the quantum annealing while the microwave fields driving play a role of the transverse fields. To quantify the performance of our scheme, we implement numerical simulations, and show that we can obtain ground states of the two-dimensional Heisenberg model with a high fidelity.

  • Quantum remote sensing under the effect of dephasing

    Hideaki Okane, Hideaki Hakoshima, Yuki Takeuchi, Yuya Seki, Yuichiro Matsuzaki

    Physical Review A (American Physical Society (APS))  104 ( 6 )  2021.12

    Accepted,  ISSN  24699926

    　View Summary

    The quantum remote sensing (QRS) is a scheme to add security about the measurement results of a qubit-based sensor. A client delegates a measurement task to a remote server that has a quantum sensor, and eavesdropper (Eve) steals every classical information stored in the server side. By using quantum properties, the QRS provides an asymmetricity about the information gain where the client gets more information about the sensing results than Eve. However, quantum states are fragile against decoherence, and so it is not clear whether such a QRS is practically useful under the effect of realistic noise. Here, we investigate the performance of the QRS with dephasing during the interaction with the target fields. In the QRS, the client and server need to share a Bell pair, and an imperfection of the Bell pair leads to a state preparation error in a systematic way on the server side for the sensing. We consider the effect of both dephasing and state preparation error. The uncertainty of the client side decreases with the square root of the repetition number M for small M, which is the same scaling as the standard quantum metrology. On the other hand, for large M, the state preparation error becomes as relevant as the dephasing, and the uncertainty decreases logarithmically with M. We compare the information gain between the client and Eve. This leads us to obtain the conditions for the asymmetric gain to be maintained even under the effect of dephasing. Then, we can quantify how much information the client can gain while preserving the information asymmetricity.

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Reviews, Commentaries, etc. 【 Display / hide 】

  • Black-box Optimization by Annealing Machines

    Shu Tanaka, Masashi Yamashita, Yuya Seki

    The Brain &amp; Neural Networks (Japanese Neural Network Society)  29 ( 4 ) 164 - 173 2022.12

    Last author,  ISSN  1340-766X

  • 量子アニーリングやイジングマシンを用いた物質設計

    田中宗, 関優也

    理論化学会会誌「フロンティア」 4 ( 4 ) 196 - 200 2022.10

  • Boltzmann machine learning with a variational quantum algorithm

    神宮裕汰, 神宮裕汰, 関優也, 渡部昌平, 遠藤傑, 松崎雄一郎, 川畑史郎, 二国徹郎, 箱嶋秀昭

    日本物理学会講演概要集(CD-ROM) 76 ( 1 )  2021

    ISSN  2189-079X

  • 量子アニーリングの現状と未来

    Shohei, Watabe, Yuya, Seki, Shiro, Kawabata

    理大科学フォーラム (東京理科大学)  37 ( 2 ) 12 - 15 2020.04

    ISSN  1346-1206

  • 量子コンピュータと量子アニーリングマシンによる量子シミュレーション

    関 優也, 川畑 史郎

    数理科学 (サイエンス社)  57 ( 1 ) 40 - 46 2019.01

    ISSN  0386-2240

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Presentations 【 Display / hide 】

  • アニーリングマシン実機に向けたFactorization Machineによるハミルトニアン学習

    関優也

    量子アニーリング及び関連技術の基礎から社会実装まで, 

    2023.02
    , 

    Oral presentation (invited, special)

  • 21pBT-8 Order of quantum phase transition in the Wajnflasz-Pick model with phase-shift transition

    Seki Y., Tanaka S.

    Meeting Abstracts of the Physical Society of Japan, 

    2016
    , 

    The Physical Society of Japan (JPS)

  • 17aCQ-1 Control of order of quantum phase transition in the Wajnflasz-Pick model

    Seki Y., Tanaka S.

    Meeting Abstracts of the Physical Society of Japan, 

    2015
    , 

    The Physical Society of Japan (JPS)

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • 反強磁性的な量子揺らぎを用いた量子アニーリングの研究

    2013.04
    -
    2016.03

    日本学術振興会, 科学研究費助成事業 特別研究員奨励費, 特別研究員奨励費, No Setting

    　View Summary

    ・研究の成果
    Quditを用いた量子アニーリングと量子相転移現象との関連についての研究を行った．量子アニーリングは，2つの準位を持つqubitを用いた系で実行されることを通常は想定されている．しかしながら，もっと多くの順位を持つ系を用いた量子アニーリングを構成することも可能である．多数の順位を導入した時，その準位間の量子的遷移の可能性が新たに生まれるため，その遷移を制御することで量子アニーリングの効率が変わることが期待される．量子2準位系の自然な拡張として考えられるWajnflasz-Pick模型を解析した．その結果，模型の準位数やその間の遷移を変化させることで量子相転移現象が変化することが確かめられた．具体的にわかった内容は次の通りである．(1) 上スピンと下スピン状態の縮退数が同じで縮退している状態間の遷移を表すパラメータが正の場合，あるいは縮退している準位間の遷移が無い場合，系は通常の２準位系と同じ振る舞いを示すことがわかった．(2) 縮退数が異なりかつ遷移を表すパラメータが非ゼロの正の実数の場合，もともとの2準位系では存在しなかった１次の量子相転移が起こることがわかった．
    <BR>
    ・意義と重要性
    量子アニーリングは組合せ最適化問題を解くための手法の一つである．組合せ最適化問題の効率的解法を探索することは社会に対し大きな貢献をする．なぜならば，物流の配送ルートの短縮化やタンパク質の構造解析などの様々な分野で組合せ最適化問題が現れるからである．Quditを用いた量子アニーリングの解析はこれまであまりされていなかった．実際に量子アニーリングを実行する際に上述した多準位系を用いることは可能であり，その際の量子アニーリングの効率を知っておくことは，組合せ最適化問題の効率的解法を探索する上で重要である．

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Awards 【 Display / hide 】

  • 第14回日本物理学会若手奨励賞（領域11）

    関優也, 2020.03, 日本物理学会, Non-stoquastic 演算子による量子アニーリングの高速化

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Memberships in Academic Societies 【 Display / hide 】

  • 日本物理学会, 

    2011.11
    -
    Present
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