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金城 佳世（キンジョウ カヨ）
| 理工学研究科 数理電子情報部門 | 助教 |
| 工学部 情報工学科 |
業績情報
■ 論文- Permutation of Tensor-Train Cores for Computing Moments on Stochastic Differential Equations
Kayo Kinjo; Rihito Sakurai; Tatsuya Kishimoto; Jun Ohkubo
Journal of the Physical Society of Japan, 巻：94, 号：8, 2025年08月
Physical Society of Japan
DOI：https://doi.org/10.7566/jpsj.94.084001
DOI ID：10.7566/jpsj.94.084001, ISSN：0031-9015, eISSN：1347-4073 - Integrated Utilization of Equations and Small Dataset in the Koopman Operator: Applications to Forward and Inverse Problems
Ichiro Ohta; Shota Koyanagi; Kayo Kinjo; Jun Ohkubo
Journal of the Physical Society of Japan, 巻：94, 号：6, 2025年05月, ［］
Physical Society of Japan
DOI：https://doi.org/10.7566/jpsj.94.064001
DOI ID：10.7566/jpsj.94.064001, ISSN：0031-9015, eISSN：1347-4073 - Comparison of gap-based and flow-based control strategies using a new controlled stochastic cellular automaton model for traffic flow
Kayo Kinjo; Akiyasu Tomoeda
Transportation Letters, 開始ページ：1, 終了ページ：11, 2024年10月, ［］
Informa UK Limited
DOI：https://doi.org/10.1080/19427867.2024.2417150
DOI ID：10.1080/19427867.2024.2417150, ISSN：1942-7867, eISSN：1942-7875 - Improvement of System Identification of Stochastic Systems via Koopman Generator and Locally Weighted Expectation
Yuki Tahara; Kakutaro Fukushi; Shunta Takahashi; Kayo Kinjo; Jun Ohkubo
Journal of the Physical Society of Japan, 巻：93, 号：7, 開始ページ：074006-1, 終了ページ：074006-9, 2024年07月, ［］
Physical Society of Japan
DOI：https://doi.org/10.7566/jpsj.93.074006
DOI ID：10.7566/jpsj.93.074006, ISSN：0031-9015, eISSN：1347-4073 - Extraction of nonlinearity in neural networks with Koopman operator
Naoki Sugishita; Kayo Kinjo; Jun Ohkubo
Journal of Statistical Mechanics: Theory and Experiment, 巻：2024, 号：7, 開始ページ：073401, 終了ページ：073401, 2024年07月, ［］
Abstract
Nonlinearity plays a crucial role in deep neural networks. In this paper, we investigate the degree to which the nonlinearity of the neural network is essential. For this purpose, we employ the Koopman operator, extended dynamic mode decomposition, and the tensor-train format. The Koopman operator approach has been recently developed in physics and nonlinear sciences; the Koopman operator deals with the time evolution in the observable space instead of the state space. Since we can replace the nonlinearity in the state space with the linearity in the observable space, it is a hopeful candidate for understanding complex behavior in nonlinear systems. Here, we analyze learned neural networks for the classification problems. As a result, the replacement of the nonlinear middle layers with the Koopman matrix yields enough accuracy in numerical experiments. In addition, we confirm that the pruning of the Koopman matrix gives sufficient accuracy even at high compression ratios. These results indicate the possibility of extracting some features in the neural networks with the Koopman operator approach.
IOP Publishing
DOI：https://doi.org/10.1088/1742-5468/ad5713
DOI ID：10.1088/1742-5468/ad5713, eISSN：1742-5468 - Dynamics of quantum double dark-solitons and an exact finite-size scaling of Bose–Einstein condensation
Kayo Kinjo; Jun Sato; Tetsuo Deguchi
Journal of Physics A: Mathematical and Theoretical, 巻：56, 号：16, 開始ページ：164001, 終了ページ：164001, 2023年03月, ［］
Abstract
We show several novel aspects in the exact non-equilibrium dynamics of quantum double dark-soliton states in the Lieb–Liniger model for the one-dimensional Bose gas with repulsive interactions. We also show an exact finite-size scaling of the fraction of the quasi-Bose–Einstein condensation (BEC) in the ground state, which should characterize the quasi-BEC in quantum double dark-soliton states that we assume to occur in the weak coupling regime. First, we show the exact time evolution of the density profile in the quantum state associated with a quantum double dark-soliton by the Bethe ansatz. Secondly, we derive a kind of macroscopic quantum wave-function effectively by exactly evaluating the square amplitude and phase profiles of the matrix element of the field operator between the quantum double dark-soliton states. The profiles are close to those of dark-solitons particularly in the weak-coupling regime. Then, the scattering of two notches in the quantum double dark-soliton state is exactly demonstrated. It is suggested from the above observations that the quasi-BEC should play a significant role in the dynamics of quantum double dark-soliton states. If the condensate fraction is close to 1, the quantum state should be well approximated by the quasi-BEC state where the mean-field picture is valid.
IOP Publishing
DOI：https://doi.org/10.1088/1751-8121/acc496
DOI ID：10.1088/1751-8121/acc496, ISSN：1751-8113, eISSN：1751-8121 - Quantum Dark Solitons in the 1D Bose Gas: From Single to Double Dark-Solitons
Kayo Kinjo; Eriko Kaminishi; Takashi Mori; Jun Sato; Rina Kanamoto; Tetsuo Deguchi
Universe, 巻：8, 号：1, 開始ページ：2, 終了ページ：2, 2021年12月, ［］
We study quantum double dark-solitons, which give pairs of notches in the density profiles, by constructing corresponding quantum states in the Lieb–Liniger model for the one-dimensional Bose gas. Here, we expect that the Gross–Pitaevskii (GP) equation should play a central role in the long distance mean-field behavior of the 1D Bose gas. We first introduce novel quantum states of a single dark soliton with a nonzero winding number. We show them by exactly evaluating not only the density profile but also the profiles of the square amplitude and phase of the matrix element of the field operator between the N-particle and (N−1)-particle states. For elliptic double dark-solitons, the density and phase profiles of the corresponding states almost perfectly agree with those of the classical solutions, respectively, in the weak coupling regime. We then show that the scheme of the mean-field product state is quite effective for the quantum states of double dark solitons. Assigning the ideal Gaussian weights to a sum of the excited states with two particle-hole excitations, we obtain double dark-solitons of distinct narrow notches with different depths. We suggest that the mean-field product state should be well approximated by the ideal Gaussian weighted sum of the low excited states with a pair of particle-hole excitations. The results of double dark-solitons should be fundamental and useful for constructing quantum multiple dark-solitons.
MDPI AG
DOI：https://doi.org/10.3390/universe8010002
DOI ID：10.3390/universe8010002, eISSN：2218-1997
- 非線形シュレーディンガー方程式におけるギャップソリトン解とソリトン解のつながり
金城佳世; 上西慧理子; 森貴司; 佐藤純; 出口哲生
日本物理学会講演概要集(CD-ROM), 巻：76, 号：1, 2021年
ISSN：2189-079X, J-Global ID：202102218569211750 - 量子ダークソリトン状態の行列要素の考察
金城佳世; 上西慧理子; 森貴司; 佐藤純; 出口哲生
日本物理学会講演概要集(CD-ROM), 巻：76, 号：2, 2021年
ISSN：2189-079X, J-Global ID：202202237759651474 - リープ・リニガー模型での2ダークソリトン解の試み:古典ソリトン解の構成
金城佳世; 上西慧理子; 森貴司; 佐藤純; 出口哲生
日本物理学会講演概要集(CD-ROM), 巻：75, 号：1, 2020年
ISSN：2189-079X, J-Global ID：202002228119662856 - 非線形シュレーディンガー方程式の準周期解の応用とリープ・リニガー模型
金城佳世; 上西慧理子; 森貴司; 佐藤純; 出口哲生
日本物理学会講演概要集(CD-ROM), 巻：75, 号：2, 2020年
ISSN：2189-079X, J-Global ID：202102268976334393 - 量子ダークソリトンのダイナミクス 2
金城佳世; 上西慧理子; 森貴司; 佐藤純; 出口哲生
日本物理学会講演概要集(CD-ROM), 巻：74, 号：2, 2019年
ISSN：2189-079X, J-Global ID：202002295398130867
- 双対過程における微分方程式系の解法としてのテンソル・トレイン形式
金城 佳世; 大久保 潤
日本物理学会第79回年次大会, 2024年09月
口頭発表（一般） - Computing Statistics of Stochastic Differential Equations Via Tensor-Train Format
Kayo KINJO; Jun OHKUBO
2024 SIAM Conference on Nonlinear Waves and Coherent Structures
2024年06月 - 2024年06月, 英語, ポスター発表
- 2024年04月 - 現在
プログラミング演習II, 埼玉大学 - 2024年09月 - 2025年01月
線形代数学演習II, お茶の水女子大学 - 2024年04月 - 2024年08月
プログラミング演習III, 埼玉大学 - 2024年04月 - 2024年08月
線形代数学演習I, お茶の水女子大学
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