News
55 news in 2026
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2026-05-07
Paper of the WeekWeek 2, May 2026
Title: Implementation of the Habegger--Lin decision algorithm Author: Yuka Kotorii, Atsuhiko Mizusawa arXiv: http://arxiv.org/abs/2605.04433v1 Title: Quasinormal modes and continuum response of de Sitter black holes via complex scaling method Author: Shoya Ogawa, Okuto Morikawa, Takuya Hirose arXiv: http://arxiv.org/abs/2605.03277v1 Title: Generalized Free Fields in de Sitter from 1D CFT Author: Kanato Goto, Alexey Milekhin, Herman Verlinde, Jiuci Xu arXiv: http://arxiv.org/abs/2605.03037v1 Title: Loop expansion in polymer field theory: application to phase separation Author: Kiyoharu Kawana, Kyosuke Adachi arXiv: http://arxiv.org/abs/2605.01261v1 Title: A variational approach to estimating the state of a magma reservoir from observed displacement Author: Shungo Kun Tonoyama, Atsushi Suzuki, Takemasa Miyoshi arXiv: http://arxiv.org/abs/2605.00409v1 Title: Examination of the $c\bar{c}+n+^{10}$Be bound-state problem within three cluster models based on QCD charmonium-nucleon interactions Author: Faisal Etminan arXiv: http://arxiv.org/abs/2604.27652v1 Title: Anomalous tunneling as a low-energy theorem for Nambu-Goldstone modes Author: Keisuke Fujii, Daichi Kagamihara, Masaru Hongo arXiv: http://arxiv.org/abs/2604.27489v1
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2026-04-30
Award
Takumi Doi Receives the Awards for Science and Technology (Research Category) in the FY2026 Commendation for Science and Technology by MEXT
Takumi Doi (Senior Research Scientist, iTHEMS) has received the Awards for Science and Technology (Research Category) in the FY2026 Commendation for Science and Technology by MEXT. This award is given to researchers who have achieved outstanding research accomplishments. He was honored for his research entitled “ First-Principles Studies of Realistic Hadron Interactions and Exotic Hadrons.” Congratulations, Takumi!
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2026-04-30
Hot Topic
Farewell message from Iao-Fai Io
Our colleague, Iao-Fai Io, will be returning to National Taiwan University starting in May to complete his Ph.D. We will miss him and wish him all the best in his future career. Here is a message from Iao-Fai: I joined iTHEMS in May 2025 as an International Program Associate (IPA). Over the past year, I have been very happy to be part of the iTHEMS member. RIKEN is one of national research institute in Japan, during my time here I had the opportunity to attend many high-quality seminars and workshops. I have also had the opportunity to visit and interact with member from different centers in RIKEN(such as CEMS, FQSP, RQC, etc.). I am also very grateful for the “coffee meetings” and “iTHEMS Now & Next” events, which helped me understand iTHEMS and learn about research which is beyond my own field. I would like to express my sincere gratitude to my host researcher, Dr. Ching-Kai Chiu. He has taught me a great deal about research, particularly in superconductivity and altermagnetism, which has significantly improved my research abilities in condensed matter theory. Whenever I encountered difficulties in my research, he was always willing to discuss them with me and suggest valuable advice. I am also grateful to him for introducing me his collaborators, including Congcong Le (a former iTHEMS member) and collaborators from China. In addition, I would like to thank him for his support during my visits abroad. I would also like to thank Tomoko Iwanami-san and Chikako Ota-san for their administrative support. In addition, I am grateful to all the people I have met at iTHEMS over the past year (such as Yan, Xiaoyang, Duc-Truyen, Tianyin, Zhe, Jinyang, Rumi, Yuta, Brian, Shuntaro, Lingxiao, Muzi, Sho, Satsuki, Iso, Haruki, Tada, Hatsuda, etc.). Over the coming year, I will return to National Taiwan University to complete my Ph.D., while also beginning to apply for postdoctoral positions. In the future, if I have the opportunity, I would be happy to visit RIKEN iTHEMS again. I sincerely hope to see you all again in the near future.
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2026-04-30
Paper of the WeekWeek 5, April 2026
Title: Chimera states on m-directed hypergraphs Author: Rommel Tchinda Djeudjo, Timoteo Carletti, Hiroya Nakao, Riccardo Muolo doi: https://doi.org/10.1103/j1zm-98yt arXiv: http://arxiv.org/abs/2506.12511v5
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2026-04-27
Award
Ryusuke Hamazaki Receives the Young Scientists’ Award from MEXT
Ryusuke Hamazaki (RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR) / Senior Research Scientist, iTHEMS) has received the Young Scientists’ Award in the FY2026 Commendation for Science and Technology by MEXT. This award recognizes early-career researchers who have achieved outstanding research accomplishments. He was honored for his research entitled “Studies on universality and novel phases in nonequilibrium quantum many-body systems.” Congratulations, Ryusuke!
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2026-04-23
Paper of the WeekWeek 4, April 2026
Title: Interaction between nuclear clusters and superfluid phonons in the neutron-star inner crust Author: Masayuki Matsuo, Arata Nishiwaki, Toshiyuki Okihashi, Masaru Hongo arXiv: http://arxiv.org/abs/2604.20725v1 Title: Complex scaling approach to quasinormal modes of Schwarzschild and Reissner--Nordström black holes Author: Shoya Ogawa, Takuya Hirose, Okuto Morikawa arXiv: http://arxiv.org/abs/2604.20442v1 Title: Understanding supernova gravitational waves with protoneutron star asteroseismology Author: Hajime Sotani arXiv: http://arxiv.org/abs/2604.19557v1 Title: Merger rate of initially clustered primordial black holes for the two-body channel Author: Kentaro Kasai, Masahiro Kawasaki, Kai Murai, Shunsuke Neda arXiv: http://arxiv.org/abs/2604.19316v1 Title: A unified framework for efficient quantum simulation of nonlinear spectroscopy Author: Long Xiong, Xiaoyang Wang, Xiaoxia Cai, Xiao Yuan arXiv: http://arxiv.org/abs/2604.16164v1 Title: PSMC-FAC: Automated Optimization of False-Negative Rate Corrections for Low-Coverage PSMC-Based Demographic Inference Author: Francisco Iglesias-Santos, Alba Nieto, Sònia Casillas, Antonio Barbadilla, Carlos Sarabia Journal Reference: Biology 2026, 15(8), 631 doi: https://doi.org/10.3390/biology15080631
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2026-04-23
Hot Topic
The third RIKEN Quantum internal meeting on March 30, 2026
On Monday, March 30, the third RIKEN Quantum internal meeting was held in the Large Conference Room (2F, Administrative Headquarters) at RIKEN, Wako, attended by a total of over 50 RIKEN Quantum members and related researchers. At this meeting, Yahui Chai and Danny Jammooa, who were invited from overseas, gave presentations on their recent research, 'Quantum Simulation of Particle Scattering' and 'Parametric Matrix Models,' respectively. Furthermore, Jian Xu, who recently joined RIKEN Quantum, presented the research he plans to pursue at the institute. In addition, 12 researchers from various fields associated with RIKEN Quantum, who also serve as RIKEN TRIP visiting scientists for collaborative projects, gave short talks to introduce their work. At the banquet following the meeting, members, including those meeting for the first time, exchanged ideas in a relaxed atmosphere, leading to fruitful discussions for the further development of RIKEN Quantum. Reported by Shinichiro Fujii
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2026-04-21
Award
Keiya Hirashima received FY2025 RIKEN Research and Technology Incentive Award (RIKEN OHBU Award 理研桜舞賞)
Keiya Hirashima (Special Postdoctoral Researcher, iTHEMS) has been awarded the FY2025 RIKEN Research and Technology Incentive Award (RIKEN OHBU Award). The RIKEN OHBU Award is presented to early-career researchers and staff members at RIKEN who have demonstrated outstanding achievements in research and development, research support, or contributions to the promotion and dissemination of research outcomes, through active research activities. Hirashima was recognized for his work entitled “Establishment of galaxy simulations resolving individual stars through the integration of AI surrogate models and large-scale parallel computing.” This work integrates advanced AI surrogate modeling with large-scale parallel computation to enable high-resolution galaxy simulations that resolve individual stars, contributing to a deeper understanding of galaxy formation and evolution. Congratulations, Keiya!
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2026-04-21
Award
Masazumi Honda received FY2025 RIKEN Excellent Achievement Award (RIKEN BAIHO Award 理研梅峰賞)
Masazumi Honda (Senior Research Scientist, iTHEMS) has been awarded the FY2025 RIKEN Excellent Achievement Award (RIKEN BAIHO Award). The RIKEN BAIHO Award is presented by the President of RIKEN to individuals who have achieved original and outstanding research and development results that are expected to receive high recognition in academic communities, or who have made distinguished contributions to research support both within and outside the institute. Honda was recognized for his work entitled “Development of non-perturbative methods in quantum field theory and quantum gravity.” This work develops novel theoretical approaches to analyze strongly coupled phenomena in quantum field theory and quantum gravity, and is expected to contribute to the advancement of fundamental physics through a deeper understanding of non-perturbative dynamics. Congratulations, Masazumi!
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2026-04-21
Award
Leo Speidel, RIKEN ECL Research Unit Leader, Receives the SMBE Early-Career Excellence Award
Leo Speidel, RIKEN ECL Research Unit Leader of the Mathematical Genomics RIKEN ECL Research Unit, Division of Fundamental Mathematical Science, RIKEN iTHEMS, has been awarded the 2026 SMBE Early-Career Excellence Award on March 12, 2026. This award is presented by the Society for Molecular Biology and Evolution (SMBE) to researchers who have made significant contributions to the advancement of the field through innovative research and who embody the values of the society through activities such as education and outreach. He has advanced research on genetic data analysis using mathematical approaches, providing new insights into molecular evolution and population genetics. This award recognizes his research achievements and contributions to the field. Congratulations, Leo!
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2026-04-16
Paper of the WeekWeek 3, April 2026
Title: Generalised (bi-)Hamiltonian structures of hydrodynamic type and (bi-)flat F-manifolds Author: Paolo Lorenzoni, Zhe Wang arXiv: http://arxiv.org/abs/2604.12819v1 Title: Interaction-powered Type Ibn Supernovae as a Transient PeVatron Candidate: The Case of SN 2023uqf Author: Ryo Sawada, Yusuke Inoue, Yosuke Ashida arXiv: http://arxiv.org/abs/2604.12496v1 Title: Exact SL(2,Z)-Structure of Lattice Maxwell Theory with $θ$-term in Modified Villain Formulation Author: Shoto Aoki, Yoshio Kikukawa, Toshinari Takemoto arXiv: http://arxiv.org/abs/2604.08736v1
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2026-04-10
Hot Topic
Talk Event “Useless Science & Art” Held at the Museum of Contemporary Art Tokyo
As a related program of the Mission∞Infinity exhibition at the Museum of Contemporary Art Tokyo, the talk event “Useless Science & Art: The Usefulness of ‘Useless’ Science and Art” was held on Saturday, March 21, 2026, attracting 119 participants. This event was organized as a continuation of “Entangle Moment [Quantum, Sea, and Universe] × Art,” held at the EXPO Messe “WASSE” during Expo 2025 Osaka, Kansai, from August 14 to 20, 2025, which welcomed approximately 60,000 visitors in total. Continuing the momentum of that initiative, the event brought together iTHEMS researchers and artists to discuss the value of scientific research and artistic expression that may initially appear “useless.” Using Black Hole Recorder, a work inspired by quantum black hole theory, as a starting point, participants shared multifaceted perspectives on the relationship between science and creativity. Audience members also actively engaged in the discussion, raising numerous questions and exchanging ideas about the relationship between science and art and how their value should be understood. The venue was filled with lively and enthusiastic discussion throughout the event. Expanding further on the fusion of science and art sparked by the Expo, the event provided a valuable opportunity to reflect on the nature of knowledge from a long-term perspective. The Mission∞Infinity: Space, Quantum, and Art exhibition at the Museum of Contemporary Art Tokyo, including the display of Useless Prototyping Studio’s Black Hole Recorder, will continue through Wednesday, May 6, 2026 (national holiday).
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2026-04-09
Award
Ryo Sawada Receives the Young Investigator Award from the Japan Forum of Nuclear Astrophysics (UKAKUREN)
Ryo Sawada, a Special Postdoctoral Researcher at RIKEN iTHEMS, received the 2nd Young Investigator Award from the Japan Forum of Nuclear Astrophysics (UKAKUREN) on March 31, 2026. The research recognized with this award concerns the impact of cosmic-ray environments originating from past supernovae on the formation of Earth-like planets [1]. Congratulations Ryo!
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2026-04-09
Award
Akira Dohi Receives the Young Investigator Award from the Japan Forum of Nuclear Astrophysics (UKAKUREN)
Akira Dohi, a Special Postdoctoral Researcher at the RIKEN Pioneering Research Institute (PRI) and concurrently affiliated with RIKEN iTHEMS, received the 2nd Young Investigator Award from the Japan Forum of Nuclear Astrophysics (UKAKUREN) on March 31, 2026. The paper [1], recognized with this award, presents a theoretical study of clocked X-ray bursters. This work also represents the scientific result from NinjaSat, the world’s first ultra-small general-purpose X-ray satellite, launched on November 11, 2023 under the leadership of the Tamagawa High-Energy Astrophysics Laboratory at RIKEN PRI. For further details, please refer to the press release issued by RIKEN PRI via the related link. Congratulations Akira!
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2026-04-09
Paper of the WeekWeek 2, April 2026
Title: Twisted doughnuts: Thick disk torus around equatorial asymmetric black hole Author: Che-Yu Chen, Eva Hackmann, Audrey Trova arXiv: http://arxiv.org/abs/2604.05604v1 Title: Gauss law codes and vacuum codes from lattice gauge theories Author: Javier P. Lacambra, Aidan Chatwin-Davies, Masazumi Honda, Philipp A. Hoehn arXiv: http://arxiv.org/abs/2604.06087v1 Title: Reconstruction of fast-rotating neutron star observables with the neural network Author: Wen Liu, Lingxiao Wang, Zhenyu Zhu arXiv: http://arxiv.org/abs/2604.05428v1 Title: Electroweak Doublet Dark Matter for a Galactic Halo Gamma-Ray Excess Author: Yasunori Nomura, Tomonori Totani arXiv: http://arxiv.org/abs/2604.05016v1 Title: Cosmological collider signals of modular spontaneous CP breaking Author: Shuntaro Aoki, Alessandro Strumia arXiv: http://arxiv.org/abs/2604.05548v1 Title: Mechanochemical instabilities drive digit morphogenesis in organoids Author: Rio Tsutsumi, Antoine Diez, Steffen Plunder, Ryuichi Kimura, Shinya Oki, Kaori Takizawa, Rei Nakano, Haruhiko Akiyama, Ritsuko Takada, Shinji Takada, Marco Musy, James Sharpe, Mototsugu Eiraku doi: https://doi.org/10.1101/2025.08.31.673315 Title: Multi-field oscillons/I-balls in the Friedberg-Lee-Sirlin model Author: Kai Murai, Tatsuya Ogawa, Fuminobu Takahashi arXiv: http://arxiv.org/abs/2604.04494v1 Title: Exponentially Long Evaporation of Noncommutative Black Hole Author: Pei-Ming Ho, Wei-Hsiang Shao, Takuya Yoda arXiv: http://arxiv.org/abs/2604.04774v1 Title: Type-IV 't Hooft Anomalies on the Lattice: Emergent Higher-Categorical Symmetries and Applications to LSM Systems Author: Tsubasa Oishi, Hiromi Ebisu arXiv: http://arxiv.org/abs/2604.02856v1 Title: Continuous-time evolution via probabilistic angle interpolation and its applications Author: Tomoya Hayata, Yuta Kikuchi arXiv: http://arxiv.org/abs/2604.02854v1 Title: Phase transitions in parametrized quantum circuits Author: Xiaoyang Wang, Han Xu, Lukas Broers, Tomonori Shirakawa, Seiji Yunoki arXiv: http://arxiv.org/abs/2603.27532v1 Title: Angular momentum transport in the convection zone of a 3D MHD simulation of a rapidly rotating core-collapse progenitor Author: Ryota Shimada, Lucy O. McNeill, Vishnu Varma, Keiichi Maeda, Takaaki Yokoyama, Bernhard Müller arXiv: http://arxiv.org/abs/2603.26550v1 Title: Cosmology from asymptotically safe Proca theories Author: Carlos Pastor-Marcos, Lavinia Heisenberg, Álvaro Pastor-Gutiérrez, Jan M. Pawlowski, Manuel Reichert arXiv: http://arxiv.org/abs/2604.01090v1 Title: Lindbladian Simulation with Commutator Bounds Author: Xinzhao Wang, Shuo Zhou, Xiaoyang Wang, Yi-Cong Zheng, Shengyu Zhang, Tongyang Li arXiv: http://arxiv.org/abs/2603.28602v1 Title: Disentangling the interactive effects of anthropogenic disturbances on biodiversity Author: Isaac Planas-Sitjà, Ryosuke Iritani, Adam L. Cronin arXiv: http://arxiv.org/abs/2603.29116v1 Title: Gravitational waves from gaps of neutron stars Author: Akira Dohi, Asuka Ito, Shota Kisaka arXiv: http://arxiv.org/abs/2603.29514v1 Title: Universal Non-Gaussian Signatures from Transient Instabilities Author: Shuntaro Aoki, Diederik Roest, Denis Werth arXiv: http://arxiv.org/abs/2604.01035v1 Title: Evaluating Phylogenetic Comparative Methods under Reticulate Evolutionary Scenarios Author: Lydia Morley, Emma Lehmberg, Sungsik Kong arXiv: http://arxiv.org/abs/2603.25986v1 Title: Segmentation of monotone data by Kobayashi-Warren-Carter type total variation energies Author: Yoshikazu Giga, Ayato Kubo, Hirotoshi Kuroda, Koya Sakakibara arXiv: http://arxiv.org/abs/2603.28078v2 Title: Zeta Zeros in a Narrow Vertical Box Author: Daniel A. Goldston, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2603.28104v1 Title: Finite-nuclear-size effect for hydrogenlike ions under high external pressure Author: Dengshan Liu, Huihui Xie, Pengxiang Du, Tianshuai Shang, Jian Li, Jiguang Li, Tomoya Naito arXiv: http://arxiv.org/abs/2603.22901v1
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2026-04-06
Person of the Week
Self-introduction: Yuta Hamada
I am interested in particle physics such as string theory and early universe cosmology. Recently, I am working on identifying consistent gravitational effective field theories that can be ultraviolet completed. Additionally, I am interested in applying AI and quantum computing to string theory and quantum field theory.
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2026-04-02
Hot Topic
KEK-iTHEMS Workshop “Concepts of Quantum and Spacetime” on March 9, 2026
We held the workshop “Concepts of Quantum and Spacetime” (at KEK in Japan from 9 to 12 March 2026), a joint workshop organized by KEK Theory Center and RIKEN iTHEMS. The two fundamental questions, “What is quantum?” and “What is spacetime?”, are deeply intertwined. The workshop discussed the question “How can quantum theory and spacetime be understood in a consistent manner?” from a fundamental and broad perspective and shared various ideas with open minds, to find directions guiding quantum theory over the next 100 years. The topics were diverse: foundations of quantum theory, quantum gravity, emergence of spacetime, formulation of semi-classical gravity, experimental aspects of fundamental properties in nature, and foundations of quantum many-body systems and thermodynamics. Around 90 researchers from various countries, generations, and fields came together. (Around 40% of these were from overseas.) The 14 keynote speakers—many of whom are rarely seen in Japan—shared their visions on quantum theory and spacetime. (The talk slides are available in the website.) The 13 selected short talks and the 22 poster presentations were of a high standard, leading to lively discussions; we also held a poster award competition. Interestingly, the disagreements and confusion arising from differences in their expertise and viewpoints actually gave rise to new discussions and ideas. This was likely due to the open atmosphere of sincere engagement that emerged because the thema was not confined to specific methods or theoretical frameworks. Furthermore, small yet significant touches—such as providing boxed lunches to keep the lively atmosphere of the lecture hall going during the lunch break, and setting up whiteboards in open spaces to encourage discussion—proved effective. These efforts fostered constant, natural interaction and lively discussion throughout the venue. Participants did not merely listen; they truly shaped the workshop. (Visit the website to see photos during the event.) Many participants commented that it was an interesting and wonderful workshop. We also received feedback such as, “I gained ideas for future research,” and “This provided valuable insights for organizing future workshops.” These are the result of the deep curiosity shared by all participants regarding fundamental questions, “What is quantum?” and “What is spacetime?” It is precisely such curiosity that will naturally give rise to new ideas and collaborative research and connect the world. I hope that workshops embodying a similar spirit will be held around the world on a variety of themes in the future. Reported by Yuki Yokokura, chair of organizing committee.
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2026-04-02
Paper of the WeekWeek 1, April 2026
Title: Nonlocal operators on the lattice for the Higgs-confinement phase transition Author: Yusuke Shimada, Arata Yamamoto Journal Reference: J.Subatomic Part.Cosmol. 5, 100267 (2026) doi: https://doi.org/10.1016/j.jspc.2025.100267 Title: The 'Forgotten' Neutrons: Implications for the Propagation of High-Energy Cosmic Rays in Magnetized Astrophysical and Cosmological Structures Author: Ellis R. Owen, Kinwah Wu, Yoshiyuki Inoue, Tatsuki Fujiwara, Qin Han, Hayden P. H. Ng arXiv: http://arxiv.org/abs/2603.25060v1 Title: Josephson effects in an interaction-asymmetric junction across the BCS-BEC crossover Author: Tingyu Zhang, Hiroyuki Tajima arXiv: http://arxiv.org/abs/2603.25577v1
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2026-04-02
Person of the Week
Self-introduction: Muzi Hong
I am doing research in cosmology, especially in early universe physics. Recently, I have been working on topics such as inflation, cosmological perturbations, baryogenesis, and dark energy. Cosmology is an interdisciplinary field, and I look forward to discussing various topics in physics with researchers from other fields.
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2026-04-02
Press Release
Observation of Regular Oscillations in Magnetization with a Quantum Computer
A research group including Senior Research Scientist Tomonori Shirakawa demonstrated that discrete time crystals and discrete time quasicrystals can be stably realized for up to 100 time steps on a 133-qubit two-dimensional lattice using IBM’s superconducting quantum computer (here, one time step corresponds to one period of the drive). This result is expected to contribute to experimental validation toward digital quantum simulation of two-dimensional nonequilibrium quantum many-body systems, which are difficult to simulate using classical computation. For further details, please refer to the related link.
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2026-04-01
Award
Yuta Sekino received FY2025 RIKEN Research and Technology Incentive Award (RIKEN OHBU Award 理研桜舞賞)
Yuta Sekino (Postdoctoral Researcher, iTHEMS) has been awarded the FY2025 RIKEN Research and Technology Incentive Award (RIKEN OHBU Award). The RIKEN Ohbu Award is presented to early-career researchers and staff members at RIKEN who have demonstrated outstanding achievements in research and development, research support, or contributions to the promotion and dissemination of research outcomes, through active research activities. Sekino was recognized for his proposal entitled “Quantum simulation of spin transport using ultracold atomic gases.” This work presents a novel theoretical framework for simulating and understanding spin transport phenomena in quantum many-body systems using ultracold atom platforms, and is expected to contribute to the advancement of quantum simulation and quantum condensed matter physics. Congratulations, Yuta!
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2026-03-31
Hot Topic
Farewell message from Takashi Satomi
Our colleague, Takashi Satomi, will be joining Tokyo Denki University as a Lecturer starting April 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Takashi: I would like to share that I will be leaving my position as an SPDR at iTHEMS. Although my term was originally planned to continue, I have decided to end it early as I will start a new position as a lecturer at Tokyo Denki University from April. I have been a member of iTHEMS as an SPDR from April 2024 to March 2026. During this time, I greatly enjoyed the open and interdisciplinary environment. Discussions with researchers from different fields gave me many new ideas and perspectives, and these experiences have been very valuable for my research. I would like to express my sincere thanks to all the members at iTHEMS for their support and kindness. From April, I will continue to be affiliated with iTHEMS as a visiting researcher. I hope to continue discussions and collaborations in the future. Thank you very much for everything.
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2026-03-31
Hot Topic
Farewell message from Ryosuke Iritani
Our colleague, Ryosuke Iritani, will be joining the Graduate School of Science, The University of Tokyo, as a Project Associate Professor starting April 1, 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Ryosuke: I have spent a rewarding seven years at iTHEMS. My research interests and vision have broadened significantly thanks to the research environment here. Since joining iTHEMS in 2019, I have become increasingly interested in learning and applying mathematics to biological questions. Whenever I encounter new mathematical techniques, I naturally consider how they might be applied to biological systems and how they can bridge our fields. Through this process, I have come to appreciate the truly interdisciplinary nature of science. This shift in my mindset was made possible by the opportunity to interact with such a diverse group of researchers. My goal over the next decade is to conduct biological research that also inspires other communities, such as mathematics and physics. I look forward to seeing where this path leads. The year 2020 was an unprecedented time, not only for iTHEMS but for society as a whole. During that period, we frequently discussed how to maintain an open and productive community, considering various ways to foster engagement within iTHEMS. As we move past the pandemic, I realize that navigating those challenges was an invaluable experience. It served as an important reminder that our research is fundamentally driven by human connection, passion, and well-being, and that we are individuals first and foremost. Finally, I would like to thank all the colleagues, technical staff, assistants, promotion office staff, and directors with whom I have been fortunate to work, discuss, chat, and dine. While I cannot list everyone by name here, I am deeply grateful for every interaction that enriched my time at iTHEMS. Special thanks to Adachi-san and Hamazaki-san for our continued collaboration; to Biology Seminar, Math Seminar, and Information Theory WG members for sharing their time and ideas through our daily interactions; to Catherine, Hatsuda-san, and Iso-san for their encouragement and for fostering such a great environment; and finally, to Wada-san for the continuous support in almost all aspects of my time at iTHEMS.
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2026-03-31
Hot Topic
Farewell message from Ryo Namba
Our colleague, Ryo Namba, will be joining the Department of Physics, Faculty of Science, Shizuoka University, as a Lecturer starting April 1, 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Ryo: It has been an incredibly stimulating and encouraging five years since I joined iTHEMS in 2021. When I first arrived, restrictions due to COVID-19 limited how often we could come to the office, and I did not have many opportunities to meet other iTHEMS members in person. However, through online meetings and seminars, I sensed a strong and growing enthusiasm for intellectual exchange within the community. Once these constraints were relaxed, people naturally began to gather, and I had many valuable opportunities to interact with colleagues across a wide range of disciplines, including particle and nuclear physics, biology, and mathematics. It was during this time that I was able to expand my research directions significantly. I had the opportunity to participate in study camps with mathematicians and to organize a couple of intensive lecture series spanning physics and mathematics. These experiences have played a central role in shaping my current research focus. iTHEMS offers a truly unique research environment -- not only in its interdisciplinary nature, but also in its openness to member-driven initiatives such as workshops, seminars, and other academic activities. I am deeply grateful for my time at iTHEMS, and I look forward to building on these experiences in my research and educational aspects at Shizuoka University. I sincerely wish for the continued flourishing and development of iTHEMS, and for its current and future members to enjoy their own vibrant and productive time there.
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2026-03-31
Hot TopicFarewell message from Sotaro Sugishita
Our colleague, Sotaro Sugishita, will be joining Hokkaido University as an Associate Professor starting April 1st, 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Sotaro: I joined iTHEMS in April 2025 as a research scientist in a cross-appointment position with Kyoto University. Although my time at iTHEMS has been short, I am very grateful for the opportunity to have been part of this unique and inspiring group. Due to my busy work and life in Kyoto, it is a little unfortunate that I did not have many opportunities to visit the Wako campus in person. Nevertheless, every time I visited, I was reminded of what a remarkable place iTHEMS is. There are so many outstanding researchers at iTHEMS, and each visit provided me with new stimulation. The open and interdisciplinary atmosphere of iTHEMS is truly special, and I feel fortunate to have had the experience. I would also like to express my sincere appreciation to the assistants at iTHEMS. Their support was always thoughtful and incredibly supportive, and it helped me greatly throughout. I am deeply grateful not only for the academic environment, but also for the professional and welcoming support system that makes iTHEMS such a pleasant place. I would like to thank everyone at iTHEMS. From April 2026, I will join Hokkaido University as an associate professor. I will also be affiliated with iTHEMS as a visiting researcher. I sincerely look forward to staying in touch and to future interactions and collaborations.
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2026-03-31
Hot Topic
Farewell message from Yuta Sekino
Our colleague, Yuta Sekino, will be joining the Institute for Advanced Research at Nagoya University as a YLC Assistant Professor starting April 1st, 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Yuta: I have been at RIKEN for seven years. Starting this April, I will join the Institute for Advanced Research at Nagoya University as a YLC Assistant Professor. I first joined the Quantum Hadron Physics Laboratory (Hatsuda Lab.) at the Nishina Center in April 2019 as a JSPS fellow, and from that time I also began attending iTHEMS activities. In October 2021, I moved to the Astrophysical Big Bang Laboratory (Nagataki Lab.) at RIKEN Cluster for Pioneering Research and started a concurrent position in iTHEMS. In July 2024, I officially became a member of iTHEMS as a postdoctoral researcher associated with RIKEN Quantum, and a concurrent member in Hamzaki Hakubi Research Team. During my seven years at RIKEN, I have greatly enjoyed the research environment embracing the iTHEMS spirit of "under one roof." Since I was an undergraduate student, I have been interested in interdisciplinary studies because my main research field, cold atoms, is strongly influenced by other subfields of physics, such as solid-state, nuclear, and particle physics. Therefore, I have greatly enjoyed interactions with researchers not only in physics, but also in mathematics, biology, and data science. I have also appreciated the availability of quantum computing resources. Although I am moving to Nagoya University, I will remain affiliated as a visiting scientist. I would like to continue participating in iTHEMS activities, and I look forward to further interactions with everyone. Finally, I would like to express my sincere appreciation to all the researchers and assistants of iTHEMS for their kind support throughout my time at RIKEN.
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2026-03-31
Hot Topic
Farewell message from Shigenori Otsuka
Our colleague, Shigenori Otsuka, will be joining the Center for Environmental Remote Sensing, Chiba University, as an Associate Professor starting March 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Shigenori: I came to RIKEN in January 2013 as a postdoctoral researcher at R-CCS, and I joined iTHEMS as a concurrent member in April 2018. Since then, I have learned a lot from various iTHEMS activities, such as the iTHEMS colloquium series, the lecture series at Nara Women's University, coffee meetings, and collaborations between iTHEMS and Kyoto University. Although my research field, meteorology, has not been a major topic within iTHEMS, I found that we shared many common interests, including fluid dynamics, chaos, data assimilation, and machine learning. After my 13-year career at RIKEN, I moved to Chiba University in March 2026 as an associate professor at the Center for Environmental Remote Sensing. In May 2026, I will return to iTHEMS as a visiting scientist in the Prediction Science Research Team, so please keep in touch. Thank you very much!
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2026-03-26
Paper of the WeekWeek 5, March 2026
Title: Solving Functional Renormalization Group Equations with Neural Networks Author: Yang-yang Tan, Wei-jie Fu, Lianyi He, Lingxiao Wang arXiv: http://arxiv.org/abs/2603.21151v1 Title: A robust method for classification of chimera states Author: S. Nirmala Jenifer, Riccardo Muolo, Paulsamy Muruganandam, Timoteo Carletti arXiv: http://arxiv.org/abs/2603.22026v1 Title: An introduction to monitored quantum systems and quantum trajectories: spectrum, typicality, and phases Author: Ryusuke Hamazaki, Ken Mochizuki, Hisanori Oshima, Yohei Fuji Journal Reference: Progress of Theoretical and Experimental Physics, ptag055 (2026) doi: https://doi.org/10.1093/ptep/ptag055 arXiv: http://arxiv.org/abs/2512.19922v2 Title: Confinement without symmetry breaking in chiral gauge theories Author: Haolin Li, Álvaro Pastor-Gutiérrez, Shahram Vatani arXiv: http://arxiv.org/abs/2603.19355v1
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2026-03-24
Hot Topic
Farewell message from Kan Kitamura
Our colleague, Kan Kitamura, will be joining the Department of Mathematics, College of Science, Rikkyo University as an Assistant Professor, starting April 1, 2026. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Kan Kitamura: I joined iTHEMS as a special postdoctoral researcher (SPDR) in April, 2024. It has been a great pleasure to spend these two years in such a wonderful research environment. This department is built on a unique concept where researchers from diverse fields of theoretical science work together under one roof. Being able to casually interact with colleagues from different areas has continually stimulated my intellectual curiosity and provided me with a lot of inspiration. In 2025, iTHEMS transitioned into a center, and I feel fortunate to have been there at that time. The evolving environment kept my research experience fresh and exciting. I feel that my research has progressed well during my time here, and I have no doubt that the creative atmosphere of iTHEMS played a significant role in this. I would like to express my deep gratitude to my colleagues for the discussions, both formal and informal, and to the staff for their support. Although I will be leaving my current position, I will remain affiliated as a visiting scientist, and I hope to continue interacting with all of you. I wish iTHEMS every success and continued growth.
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2026-03-19
Paper of the WeekWeek 4, March 2026
Title: Toward bootstrapping tensor-network contractions Author: Seishiro Ono, Yanbai Zhang, Hoi Chun Po arXiv: http://arxiv.org/abs/2603.17856v1 Title: Crowdsourcing Gravitational Waves from Superradiant Axions Author: Sebastian A. R. Ellis, Orion Ning, Nicholas L. Rodd, Jan Schütte-Engel arXiv: http://arxiv.org/abs/2603.15734v1 Title: TracktorLive: an integrated real-time object tracking and response system Author: Pranav Minasandra, Vivek Hari Sridhar, Dominique G Roche, Isaac Planas-Sitjà Journal Reference: bioRxiv 2026.03.12.711471 doi: https://doi.org/10.64898/2026.03.12.711471 Title: Learning Quantum Operator Dynamics from Short-Time Data Author: Jinyang Li, Satoshi Iso, Shunji Matsuura, Lingxiao Wang, Xiaoyang Wang arXiv: http://arxiv.org/abs/2603.14699v1 Title: A low mass and radius neutron star candidate in XTE J1810-189? Author: Shoutao Ban, Helei Liu, Zhaosheng Li, Yupeng Chen, Guoliang Lü, Akira Dohi, Tomoshi Takeda, Hongbin Fan, Chunhua Zhu, Renxin Xu arXiv: http://arxiv.org/abs/2603.12962v1 Title: $\bar{D}$-meson Nucleon Scattering from Lattice QCD at the Physical Point Author: Wren Yamada, Yan Lyu, Kotaro Murakami, Takumi Doi arXiv: http://arxiv.org/abs/2603.12251v1
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2026-03-17
Award
Team Director Motoko Kotani Receives the Japan Academy Prize
Motoko Kotani, Team Director (concurrent) of the Mathematical Application Research Team, Division of Applied Mathematical Science, at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), has been selected as a recipient of the Japan Academy Prize. The Japan Academy announced on March 12, 2026, that the award recognizes the collaborative research “Discrete Geometric Analysis of Infinite Graphs with Symmetry” conducted with Toshikazu Sunada, Professor Emeritus of Meiji University and Professor Emeritus of Tohoku University. According to the award citation, the research was highly recognized for introducing the concept of the “standard realization” of crystal lattices, for studies of random walks on crystal lattices based on that concept, in particular for establishing central limit theorems and large deviation principles, and for the rediscovery of the K4 crystal and the promotion of its applications to materials science. These achievements have made important contributions to the development of discrete geometric analysis and discrete algebraic geometry from both theoretical and applied perspectives. The research recognized by this award is based on work that Team Director Kotani pursued while based at Tohoku University and the Advanced Institute for Materials Research (WPI-AIMR), Tohoku University. In 2018, iTHEMS and AIMR established the collaborative hub SUURI-COOL (Sendai): AIMR-iTHEMS Mathematical Science Laboratory. This laboratory, located on the third floor of the AIMR Main Building, aims to address fundamental questions in matter, life, and the universe, as well as basic problems in society, from the perspective of the mathematical sciences. All of us at iTHEMS extend our heartfelt congratulations to Team Director Kotani on this distinguished achievement.
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2026-03-12
Paper of the WeekWeek 3, March 2026
Title: Effective theory of surface oscillations in self-bound superfluid droplets Author: Jun Mitsuhashi, Keisuke Fujii, Masaru Hongo arXiv: http://arxiv.org/abs/2603.10304v1 Title: Phase diagram of 4D SU(3) Yang-Mills theory at $θ=π$ via imaginary theta simulations Author: Akira Matsumoto, Mitsuaki Hirasawa, Jun Nishimura, Atis Yosprakob arXiv: http://arxiv.org/abs/2603.09604v1 Title: Rovibrational energy levels of H$_2$O by quantum computing Author: Erik Lötstedt, Tamás Szidarovszky arXiv: http://arxiv.org/abs/2603.05795v1 Title: Schwinger effect in QCD and nuclear physics Author: Hidetoshi Taya arXiv: http://arxiv.org/abs/2603.07847v1 Title: Bergman space, Conformally flat 2-disk operads and affine Heisenberg vertex algebra Author: Yuto Moriwaki arXiv: http://arxiv.org/abs/2603.06491v1 Title: Mean-Field Convective Phase Separation under Thermal Gradients Author: Meander Van den Brande, François Huveneers, Kyosuke Adachi arXiv: http://arxiv.org/abs/2603.06214v1 Title: When minor issues matter: symmetries, pluralism, and polarization in similarity-based opinion dynamics Author: Brian Mintz, Daniel Simonson, Dominik Wodarz, Feng Fu, Natalia L. Komarova arXiv: http://arxiv.org/abs/2603.04939v1
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2026-03-11
Hot Topic
RIKEN–Berkeley Workshop on Quantum Gravity 2025 on October 23-24, 2025
The RIKEN–Berkeley Workshop on Quantum Gravity 2025 was held on October 23–24, 2025, at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN Wako Campus, Japan. The workshop marked the first meeting of a new collaboration between the Leinweber Institute for Theoretical Physics (LITP) at the University of California, Berkeley and iTHEMS. A total of 38 participants attended the workshop. The workshop brought together researchers working on quantum gravity and related areas to discuss recent developments and future directions in the field. The scientific program featured talks on a range of topics, including quantum aspects of spacetime, black hole physics, holography, and their connections to quantum information and condensed matter physics. The meeting provided an opportunity for researchers from Berkeley, RIKEN, and other institutions to exchange ideas and explore potential collaborations. Discussions during the workshop highlighted current progress in the field and encouraged interactions among participants from different research backgrounds. The workshop served as the first step in strengthening collaboration between LITP and iTHEMS, with the aim of promoting continued exchanges and future joint research activities between the two institutions. The workshop was organized by Gabriele Di Ubaldo (LITP Berkeley and RIKEN iTHEMS), Tetsuo Hatsuda (RIKEN iTHEMS), Masazumi Honda (RIKEN iTHEMS), Satoshi Iso (RIKEN iTHEMS), Masamichi Miyaji (RIKEN iTHEMS), Shigehiro Nagataki (RIKEN iTHEMS) and Yasunori Nomura (LITP Berkeley and RIKEN iTHEMS). Reported by Masamichi Miyaji
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2026-03-11
Hot Topic
XIIIth International Symposium on Nuclear Symmetry Energy (NuSym25) on September 8-13, 2025
The XIIIth International Symposium on Nuclear Symmetry Energy (NuSym25) was held from September 8 to 13, 2025, at the Integrated Innovation Building, RIKEN Kobe Campus. The symposium brought together approximately 78 researchers working on nuclear physics, astrophysics, and related fields to discuss recent developments in the study of the nuclear equation of state (EoS) and nuclear symmetry energy. The nuclear symmetry energy plays an important role in understanding properties of neutron-rich nuclear matter, which is relevant for nuclear structure, heavy-ion collisions, and astrophysical phenomena such as neutron stars and their mergers. The symposium aimed to connect experimental, observational, and theoretical efforts across these areas. The scientific program included invited and contributed talks covering a broad range of topics, including nuclear structure and reactions, heavy-ion collision experiments and transport model simulations, microscopic calculations of dense neutron-rich matter, and astrophysical observations of compact stars. Recent progress in multi-messenger observations of neutron stars and their implications for the nuclear equation of state were also discussed. The symposium provided an opportunity for researchers from different communities to exchange ideas and strengthen collaborations in addressing common challenges related to the nuclear equation of state. Following the main scientific sessions, a meeting of the Transport Model Evaluation Project (TMEP) was held to discuss benchmarking and uncertainty quantification in transport model simulations for heavy-ion collisions. Reported by Shuntaro Aoki
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2026-03-09
Hot Topic
RIKEN–Nara Women’s University Joint Diversity Promotion Workshop 2026 was held
Students from various courses at Nara Women’s University—including mathematics, physics, chemistry, biological sciences, and environmental sciences—visited RIKEN for two days, March 2–3. A total of 21 students (first-, second-, and third-year undergraduate students and first-year master’s students) participated in the visit. During their stay, the students toured several research facilities at RIKEN, including the Multiscale Brain Function Research Team at the RIKEN Center for Brain Science (CBS), the RIBF facility at the RIKEN Nishina Center, and the Optical Quantum Control Research Team at the RIKEN Center for Quantum Computing (RQC). At iTHEMS, they attended talks by Megumi Oya (Postdoctoral Researcher, Medical Science Data-driven Mathematics Team, iTHEMS) and Leo Speidel (iTHEMS ECL Research Unit Leader). At each laboratory, the students had the opportunity to observe cutting-edge research up close near experimental equipment and learn about ongoing research activities. During the evening networking session with RIKEN researchers, they asked questions to iTHEMS researchers and learned about researchers’ daily lives and career paths. The event provided a valuable opportunity for meaningful交流 and discussion for the students. This diversity promotion initiative is conducted jointly by the Faculty of Science at Nara Women’s University and RIKEN iTHEMS, and is organized in conjunction with a series of lectures held at Nara Women’s University.
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2026-03-05
Paper of the WeekWeek 2, March 2026
Title: Quantum anomaly for benchmarking quantum computing Author: Tomoya Hayata, Arata Yamamoto arXiv: http://arxiv.org/abs/2603.03697v1
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2026-03-04
Hot Topic
RIKEN President Makoto Gonokami Visits the RIKEN Berkeley Center
On February 26, 2026, Makoto Gonokami, President of RIKEN, visited the RIKEN Berkeley Center (Photo left). During his visit, the Center’s mission and organizational concept were introduced, followed by a tour of the office facilities. President Gonokami then met with the RIKEN Berkeley Fellows currently conducting research in UC Berkeley (UCB) and Lawrence Berkeley National Laboratory (LBNL) (Photo right). The fellows presented overviews of their research projects and shared their experiences regarding the academic and living environment in Berkeley. They highlighted the stimulating research atmosphere and discussed their perspectives for further development. Before and after the Center visit, President Gonokami also exchanged views with Steve Kahn (UCB, Dean of Mathematical and Physical Sciences), Yasunori Nomura（UCB, Director of the Leinweber Institute for Theoretical Physics）, and Hitoshi Murayama (UCB, Professor, Physics Department), and toured quantum computing facilities at Berkeley. This visit is expected to further strengthen collaboration and researcher exchange between RIKEN and Berkeley. The RIKEN Berkeley Center will continue to promote academic partnership and serve as a hub for international research collaboration. Photo left: In front of the RIKEN Berkeley Center signboard. From left to right: Center Director Iso, RIKEN President Makoto Gonokami, Wick Haxton, RIKEN Berkeley Center Director Nagataki, and Domain Director Hatsuda. Photo right: President Gonokami in discussion with RIKEN Berkeley Fellows. From left to right: Gabriele Di Ubaldo, Jan Shuette-Engel, Yuka Kanakubo, Domain Director Hatsuda, and Center
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2026-02-26
Paper of the WeekWeek 5, February 2026
Title: Out-of-time-ordered correlators for turbulent fields: a quantum-classical correspondence Author: Motoki Nakata arXiv: http://arxiv.org/abs/2602.21710v1 Title: Evidence of Nuclear Urca Process in the Ocean of Neutron-Star Superburst MAXI J1752$-$457 Author: Hao Huang, Akira Dohi, Amira Aoyama, Tomoshi Takeda, Nobuya Nishimura arXiv: http://arxiv.org/abs/2602.19018v1 Title: A $y$-ification of Khovanov homology Author: Taketo Sano arXiv: http://arxiv.org/abs/2602.17435v1 Title: Prefactorization algebras for the conformal Laplacian: Central charge and Hilbert Fock space Author: Yuto Moriwaki arXiv: http://arxiv.org/abs/2602.17549v1 Title: Variation in soldier investment is linked to the evolution of termite soldier defense strategies Author: Akiya Satoh, Isaac Planas-Sitjà, Adam L. Cronin, Nobuaki Mizumoto Journal Reference: Evol Ecol 40, 21 (2026) doi: https://doi.org/10.1007/s10682-026-10386-3
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2026-02-19
Paper of the WeekWeek 4, February 2026
Title: On the efficiency of pairwise Hamiltonian control to desynchronize the higher-order Kuramoto model Author: Martin Moriamé, Riccardo Muolo, Timoteo Carletti, Maxime Lucas arXiv: http://arxiv.org/abs/2602.15279v1 Title: Quarkyonic matter and hadron-quark crossover from an ultracold atom perspective Author: Hiroyuki Tajima, Kei Iida, Toru Kojo, Haozhao Liang arXiv: http://arxiv.org/abs/2602.14113v1 Title: Estimation of neutron star mass and radius of FRB 20240114A by identification of crustal oscillations Author: Hajime Sotani, Zorawar Wadiasingh, Cecilia Chirenti arXiv: http://arxiv.org/abs/2602.14353v1 Title: Physical Predictions in Closed Quantum Gravity Author: Yasunori Nomura, Tomonori Ugajin arXiv: http://arxiv.org/abs/2602.13387v1 Title: Symmetry Spans and Enforced Gaplessness Author: Takamasa Ando, Kantaro Ohmori arXiv: http://arxiv.org/abs/2602.11696v1 Title: Payoff equivalence and complete strategy spaces of direct reciprocity Author: Philip LaPorte, Christian Hilbe, Nikoleta E. Glynatsi, and Martin A. Nowak Journal Reference: PNAS doi: https://doi.org/10.1073/pnas.2518486123
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2026-02-12
Paper of the WeekWeek 3, February 2026
Title: Lifts of cycles in tropical hypersurfaces and the Gamma conjecture Author: Yuto Yamamoto arXiv: http://arxiv.org/abs/2602.08666v1 Title: Comprehensive Table of Calculated Huff Factors Author: Yuichi Uesaka, Tomoya Naito, Shuichiro Ebata, Megumi Niikura arXiv: http://arxiv.org/abs/2602.07501v1 Title: Conformally flat factorization homology in Ind-Hilbert spaces and Conformal field theory Author: Yuto Moriwaki arXiv: http://arxiv.org/abs/2602.08729v1 Title: Optimal interaction functions realizing higher-order Kuramoto dynamics with arbitrary limit-cycle oscillators Author: Norihisa Namura, Riccardo Muolo, Hiroya Nakao Journal Reference: Chaos 36, 023120 (2026) doi: https://doi.org/10.1063/5.0307452 Title: Forecasting Supermassive Black Hole Binary Gravitational Wave Probes: Prospects for Future Pulsar Timing Array and Space-Borne Detectors Author: Katsunori Kusakabe, Yoshiyuki Inoue, Daisuke Toyouchi, Keitaro Takahashi arXiv: http://arxiv.org/abs/2602.06789v1 Title: Quantum statistical functions Author: Haruki Emori arXiv: http://arxiv.org/abs/2602.05821v1
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2026-02-05
Award
Nagisa Hiroshima Receives the 7th (2026) Fumiko Yonezawa Memorial Prize
Nagisa Hiroshima (Visiting Scientist, iTHEMS / Associate Professor, Yokohama National University) has received the 7th (2026) Fumiko Yonezawa Memorial Prize. The Fumiko Yonezawa Memorial Prize was established by the Physical Society of Japan to recognize and encourage outstanding research achievements by early- to mid-career women physicists. In principle, the prize is awarded to researchers within 15 years of obtaining their final degree, and each year a small number of recipients (approximately five) are selected. Hiroshima has been engaged in theoretical research on dark matter, using astrophysical observations and theoretical models to investigate its properties. Her series of research achievements in dark matter studies employing astrophysical approaches was highly recognized, leading to this award. Congratulations, Nagisa!
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2026-02-05
Paper of the WeekWeek 2, February 2026
Title: Courant-Hilbert deformations of Yang-Baxter sigma models Author: Osamu Fukushima, Takaki Matsumoto, Kentaroh Yoshida arXiv: http://arxiv.org/abs/2602.04662v1 Title: Hurwitz-Radon numbers and proper actions of semisimple Lie groups Author: Kazuki Kannaka, Koichi Tojo arXiv: http://arxiv.org/abs/2602.04544v1 Title: von Neumann entropy of phase space structures in gyrokinetic plasma turbulence Author: Go Yatomi, Motoki Nakata arXiv: http://arxiv.org/abs/2602.00600v1 Title: When higher-order interactions enhance synchronization: the case of the Kuramoto model on random hypergraphs Author: Riccardo Muolo, Hiroya Nakao, Marco Coraggio arXiv: http://arxiv.org/abs/2508.10992v2 Title: Resource-Theoretic Quantifiers of Weak and Strong Symmetry Breaking: Strong Entanglement Asymmetry and Beyond Author: Yuya Kusuki, Sridip Pal, Hiroyasu Tajima arXiv: http://arxiv.org/abs/2601.20924v1 Title: Non-invertible translation from Lieb-Schultz-Mattis anomaly Author: Tsubasa Oishi, Takuma Saito, Hiromi Ebisu arXiv: http://arxiv.org/abs/2601.21625v1 Title: Probing the Diversity of Type Ia Supernova Remnants in 3-D Hydrodynamic Simulations with X-ray Spectral Synthesis Author: Yusei Fujimaru, Shiu-Hang Lee, Gilles Ferrand, Daniel Patnaude, Shigehiro Nagataki, Rüdiger Pakmor, Samar Safi-Harb, Friedrich K. Röpke, Anne Decourchelle, Ivo R. Seitenzahl arXiv: http://arxiv.org/abs/2601.20446v1
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2026-02-03
Hot Topic
“Black Hole Recorder” Exhibited in “Mission ∞ Infinity | Space + Quantum + Art”
ADK Marketing Solutions Inc. is exhibiting the interactive science-art installation “Black Hole Recorder”, created in collaboration with iTHEMS, as part of the special exhibition “Mission ∞ Infinity | Space + Quantum + Art”, currently being held at the Museum of Contemporary Art Tokyo from January 31 to May 6, 2026. This work is a prototype model of a future information storage device inspired by quantum black hole theory. Using the black hole as a metaphor for an object capable of containing enormous amounts of data, the installation invites visitors to record human voices and sounds, imagining them being delivered into the distant future or even into space. Through artworks that merge space science, quantum theory, and artistic expression, the exhibition offers a unique opportunity to experience the invisible world and explore new possibilities for the future. For more information, please see the related links.
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2026-01-29
Paper of the WeekWeek 5, January 2026
Title: Direct numerical simulation of the 't Hooft partition function and (de)confining phases Author: Okuto Morikawa, Hiroshi Suzuki arXiv: http://arxiv.org/abs/2601.20159v1 Title: Generalizable Equivariant Diffusion Models for Non-Abelian Lattice Gauge Theory Author: Gert Aarts, Diaa E. Habibi, Andreas Ipp, David I. Müller, Thomas R. Ranner, Lingxiao Wang, Wei Wang, Qianteng Zhu arXiv: http://arxiv.org/abs/2601.19552v1 Title: Well-posedness of the Langmuir film problem Author: Yoichiro Mori, Shinya Okabe, Koya Sakakibara arXiv: http://arxiv.org/abs/2601.16482v1 Title: Exploring Noisy Quantum Thermodynamical Processes via the Depolarizing-Channel Approximation Author: Jian Li, Xiaoyang Wang, Marcus Huber, Nicolai Friis, Pharnam Bakhshinezhad arXiv: http://arxiv.org/abs/2601.16317v1
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2026-01-29
Award
Erik Loetstedt Selected as a 2026 Outstanding Referee for the Physical Review Journals
Erik Loetstedt (Senior Research Scientist, iTHEMS) has been selected as one of the 2026 Outstanding Referees for the Physical Review journals published by the American Physical Society (APS). The Outstanding Referee program was established in 2008 to recognize scientists who have made exceptional contributions to the peer-review process for the Physical Review family of journals. Referees play an essential role in maintaining the high standards of the journals by helping improve the quality and readability of submitted manuscripts. Each year, only a small number of researchers are selected from among more than 100,000 active referees, based on the quality, number, and timeliness of their referee reports. He conducts research across multiple fields, including computational physics and chemistry, strong-field science, and quantum computing. His expertise and dedication to peer review have been highly appreciated, leading to this distinguished recognition. Congratulations, Erik!
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2026-01-22
Paper of the WeekWeek 4, January 2026
Title: Relic of quadrupole deformation produced in a hot neutron star era Author: Yasufumi Kojima, Akira Dohi, Shota Kisaka, Kotaro Fujisawa arXiv: http://arxiv.org/abs/2601.13550v1 Title: Onset of thermalization of q-deformed SU(2) Yang-Mills theory on a trapped-ion quantum computer Author: Tomoya Hayata, Yoshimasa Hidaka, Yuta Kikuchi arXiv: http://arxiv.org/abs/2601.13530v1 Title: Economic complexity and regional development in India: Insights from a state-industry bipartite network Author: Joel M Thomas, Abhijit Chakraborty arXiv: http://arxiv.org/abs/2601.12356v1 Title: Time delay embeddings to characterize the timbre of musical instruments using Topological Data Analysis: a study on synthetic and real data Author: Gakusei Sato, Hiroya Nakao, Riccardo Muolo Journal Reference: Eur. Phys. J. Spec. Top. (2026) doi: https://doi.org/10.1140/epjs/s11734-026-02132-1 Title: Shadow signatures and energy accumulation in Lorentzian-Euclidean black holes Author: Emmanuele Battista, Salvatore Capozziello, Che-Yu Chen arXiv: http://arxiv.org/abs/2601.10806v1 Title: Insights from the “Women in Evolutionary Biology Workshop” on gender equality in science Author: Stella Kyomen, Maria Alejandra Ramirez, Nikoleta E Glynatsi, Gisela T Rodríguez-Sánchez, Amanda de Azevedo-Lopes Journal Reference: Evolution doi: https://doi.org/10.1093/evolut/qpaf255
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2026-01-15
Hot Topic
iTHEMS Colloquium by Hiroki R. Ueda on October 10, 2025
On October 10, 2025, Dr. Hiroki Ueda, Professor at the University of Tokyo’s Graduate School of Medicine and former Team Leader at RIKEN Center for Biosystems Dynamics Research (BDR), delivered a splendid iTHEMS Colloquium talk on the Wako campus. His lecture, titled “Why Do We Sleep? The Role of Calcium and Phosphorylation in Sleep,” attracted a wide audience—not only researchers from iTHEMS but also colleagues from other RIKEN centers, including the Pioneering Research Institute (PRI) and the Center for Brain Science (CBS), as well as administrative staff. The talk was highly engaging and accessible to specialists and non-specialists alike. Dr. Ueda began with an overview of the long history of sleep research and the major unsolved questions that continue to inspire the field. He then presented his group’s recent discoveries on the role of calcium in sleep regulation. He also introduced a new theoretical framework—the WISE (Wake Inhibition Sleep Enhancement) mechanism—together with its mathematical modeling. Because sleep is closely connected to our daily lives, the audience had many questions from diverse perspectives, and Dr. Ueda kindly addressed each of them in detail. During and after the colloquium, including at the dinner that followed, we had stimulating discussions with him about his group’s model and potential new directions for sleep research and related areas of life science. We are deeply grateful to Dr. Ueda for his inspiring lecture and for sharing his broad expertise with our community. (Photos: courtesy of Assistant Chikako Ota, RIKEN iTHEMS.) Reported by Gen Kurosawa
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2026-01-15
Press Release
A New Principle for Controlling the “Butterfly Effect”
Takemasa Miyoshi (Team Principal, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS) / Team Director, Prediction Science Research Team, Division of Applied Mathematical Science, RIKEN iTHEMS), has developed a new mathematical framework for efficiently controlling chaos by turning the fundamental limitation of predictability in deterministic chaos—widely known as the “butterfly effect”—to an advantage. He proposed a “duality principle,” demonstrating that data assimilation, which forms the foundation of weather forecasting (a process that synchronizes a model with the behavior of nature using observational data), and the control of chaos are mathematically twin concepts. Rather than suppressing chaos itself, this new approach exploits the high sensitivity characteristic of chaotic systems to synchronize real-world behavior with a manageable “target trajectory” through only a small amount of “intervention.” In this way, the study theoretically outlines a path toward controlling chaos beyond the conventional limits of predictability. This achievement provides a theoretical basis for future research in disaster prevention and mitigation—for example, applying minimal interventions to synchronize real atmospheric phenomena with a “typhoon scenario that causes no damage” (a target trajectory) simulated in a model, with the aim of avoiding extreme weather events. It is also expected to have applications in a wide range of fields that exhibit chaotic behavior, including ecosystems and economics. For further details, please refer to the related links.
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2026-01-15
Press Release
A 300-Billion-Particle Milky Way Simulation Achieved with AI × Fugaku
An international collaborative research team including Keiya Hirashima, Special Postdoctoral Researcher, has achieved the world’s highest-resolution simulation of the Milky Way galaxy by utilizing the entire system of the AI and supercomputer “Fugaku” (approximately 150,000 nodes) and modeling 300 billion particles representing stars, interstellar gas, and other components—resolving the galaxy down to individual stars. This research is expected to contribute to a better understanding of the Milky Way’s spiral arm structure (the arm-like features of spiral galaxies that extend outward from the center while winding across the galactic disk), the circulation of chemical elements within the galaxy, and the origins of the materials that formed the Solar System and life. For more details, please refer to the related links.
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2026-01-15
Paper of the WeekWeek 3, January 2026
Title: Equivalence of Doubly Periodic Tangles Author: Ioannis Diamantis, Sofia Lambropoulou, Sonia Mahmoudi arXiv: http://arxiv.org/abs/2310.00822v2 Title: Relaxation Process During Complex Time Evolution In Two-Dimensional Integrable and Chaotic CFTs Author: Chen Bai, Weibo Mao, Masahiro Nozaki, Mao Tian Tan, Xueda Wen arXiv: http://arxiv.org/abs/2601.09290v1 Title: Dissipative ground-state preparation of a quantum spin chain on a trapped-ion quantum computer Author: Kazuhiro Seki, Yuta Kikuchi, Tomoya Hayata, Seiji Yunoki arXiv: http://arxiv.org/abs/2601.08137v1 Title: Coherence of Supermassive Black Hole Binary Demographics with the nHz Stochastic Gravitational Wave Background Author: Katsunori Kusakabe, Yoshiyuki Inoue, Daisuke Toyouchi arXiv: http://arxiv.org/abs/2510.10548v2 Title: Extending the Handover-Iterative VQE to Challenging Strongly Correlated Systems: $N_2$ and Fe-S Cluster Author: Pilsun Yoo, Kyungmin Kim, Eyuel E. Elala, Shane McFarthing, Aidan Pellow, Johanna I. Fuks, Doo Hyung Kang, Pratanphorn Nakliang, Jaewan Kim, Himadri Pathak, Tomonori Shirakawa, Seiji Yunoki, June-Koo Kevin Rhee arXiv: http://arxiv.org/abs/2601.06935v1 Title: Dynamics of Interfaces in the Two-Dimensional Wave-Pinning Model Author: Shunsuke Kobayashi, Koya Sakakibara, Taikei Uechi arXiv: http://arxiv.org/abs/2601.04746v1
55 news in 2026