RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) | iTHEMS

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Capturing the Echoes of Black Holes with Mathematical Precision

A research group including Ryo Namba (Senior Research Scientist, iTHEMS) has successfully demonstrated a method that systematically and precisely captures the frequency structure of rapidly decaying quasinormal modes of black holes by incorporating the mathematical technique known as exact WKB analysis. This result enables more rigorous analysis of gravitational wave signals from black holes in various theoretical models and is expected to contribute to improving the precision of future gravitational wave observations and verifying the fundamental properties of black holes with greater accuracy. For further details, please refer to the related link below:

2025-07-10
RIKEN NEWS: The Appeal of the ECL Program in Nurturing Early-Career Researchers

An interview with Leo Speidel (RIKEN ECL Research Unit Leader, Mathematical Genomics RIKEN ECL Research Unit) has been featured in the Topics section, as part of the Close-up RIKEN 2025 series on RIKEN’s research introduction page. A video interview is also available alongside the article. The RIKEN Early Career Leaders (ECL) Program was launched in 2023 to provide more substantial support for early-career researchers. Building on and expanding the previous RIKEN Hakubi Program, the ECL Program enables researchers to pursue agile and flexible research. In addition to appointing Team Leaders (equivalent to department heads or young professors at universities), the program has introduced the position of Unit Leader (equivalent to section heads or associate professors/lecturers at universities) to support outstanding young researchers with limited experience. These Unit Leaders are provided with a highly mobile and independent research environment at their host research centers. We spoke with Dr. Leo Speidel, the RIKEN ECL Research Unit Leader of the Mathematical Genomics RIKEN ECL Research Unit, Mathematical Science Core Division, at the Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), who is part of the program's first cohort. He is working to uncover human evolution and history through the study of DNA mutations, and he shared with us the appeal of the ECL Program. For more information, please see the related links below.

2025-07-08
Using viral load tests to help predict mpox severity when skin lesions first appear

A research group led by Shingo Iwami (Visiting Scientist, iTHEMS) has revealed through an international collaborative study that there is significant individual variation in the progression of skin lesions among patients infected with mpox (Clade Ia). The study also suggests that the blood viral load at the time of onset may serve as a useful indicator for predicting the progression of these symptoms. For more details, please refer to the related links.

2025-07-03
A New Intelligence Deciphering the Universe: Discovery of Anomalous Energy Emission Phenomena through Quantum × AI

A research group, including Shigehiro Nagataki (Chief Scientist, Astrophysical Big Bang Laboratory, RIKEN PRI / Deputy Director, iTHEMS) and Shunji Matsuura (Senior Research Scientist, iTHEMS), has successfully detected 113 anomalous energy (X-ray) emission events. This was achieved by constructing and applying a quantum machine learning model that integrates quantum computing with machine learning to a large-scale dataset of X-ray variability in space accumulated over approximately 24 years by the X-ray astronomical satellite XMM-Newton, operated by the European Space Agency (ESA). For more information, please refer to the related links below.

2025-07-03
Theoretical Discovery of Angular Momentum Reversal in Magnetic Vortical Matter

A collaborative research group, including Kazuya Mameda (Visiting Scientist, iTHEMS) has theoretically discovered that in quantum systems where strong magnetic fields and rotation coexist, the polarization of angular momentum becomes dominated by orbital angular momentum—originating from the particles’ orbital motion—rather than spin. This leads to a reversed direction of polarization compared to conventional expectations. For more information, please refer to the related links below.

2025-07-03
AI-Driven High-Resolution Galaxy Simulations: Accelerating Galaxy Evolution Modeling from 8 Months to 2

An international collaborative research group, including Keiya Hirashima (Special Postdoctoral Researcher, iTHEMS), has developed a surrogate model using deep learning, a form of artificial intelligence (AI), to predict the complex physical processes of supernova explosions. This model has been integrated into a galaxy simulation code for the first time. This achievement marks the first instance of accelerating high-resolution "star-by-star" galaxy simulations by performing deep learning inference in real time during the simulation—something that was previously difficult to realize. The new method is expected to contribute to detailed analysis of supernova feedback in the formation and evolution of our own Milky Way galaxy. For more information, please refer to the related links below.

2025-07-03
Bulk-Edge Correspondence of Measurement-Induced Topological Phases

A research group including Ryusuke Hamazaki (Senior Research Scientist, iTHEMS) has proposed a method to investigate the effective energy level structures and bulk topological invariants in quantum systems under measurement. Utilizing this approach, the team conducted a theoretical analysis of topological phase transitions induced by quantum measurements. Their findings revealed that zero-energy edge states originating from so-called "Majorana particles" can emerge in topological phases under continuous measurement. Furthermore, the study demonstrated that the bulk-edge correspondence, a universal principle typically known to hold in isolated quantum systems, also manifests in measurement-driven quantum systems. This work establishes a robust theoretical foundation for measurement-induced topological phase transitions. The method developed is broadly applicable to a wide class of topological phases, offering a versatile tool that may lead to a systematic and unified understanding of quantum phases induced by measurement. For more details, please refer to the related links.

2025-06-23
Success in Quantum Chemistry Calculations through Quantum–Supercomputer Collaboration

An international research team, including Senior Research Scientist Tomonori Shirakawa, has demonstrated the practical potential of quantum computing by performing calculations that combine IBM's quantum computer with RIKEN's supercomputer "Fugaku" to address quantum chemistry problems that have been difficult to analyze using conventional classical computers. In this study, by processing output data obtained from a real quantum computer with a supercomputer, the team successfully obtained scientifically meaningful results for a large-scale quantum chemical system exceeding 50 qubits for the first time. This achievement demonstrates that quantum computing is effective even for quantum chemistry problems that surpass the limitations of classical computation, marking a significant step forward toward the practical application of quantum computing. For more details, please refer to the related links.

2025-06-23
RIKEN NEWS: A New World Unlocked by a Data Geek

An interview with Catherine Beauchemin (Deputy Director, iTHEMS) has been featured in the RIKEN People section, as part of the Close-up RIKEN 2025 series on RIKEN’s research introduction page. With her quick wit, rapid-fire speech, and warm smile, she embodies the charm and potential of what it means to be human. Dr. Beauchemin is pioneering a new research field known as “virus physics.” By applying the tools of physics, she investigates viruses, unseen entities that can pose serious threats to our lives. To read the full story, please see the related link below.

2025-06-23
Developing a framework for inferring spatial biodiversity: quantifying the "beta-diversity" patterns

An international research team led by Ryosuke Iritani, Senior Research Scientist at RIKEN iTHEMS, has developed a theoretical framework to estimate the probability distribution of spatial biodiversity. This interdisciplinary work uses fuzzy set theory to formulate species presence-absence in a community, armed with analytical techniques and concepts from mathematics and theoretical physics. This work enables a quantitative assessment of differences and variations in species richness across regions, contributing to the prediction of how environmental changes in the biosphere influence biodiversity. For more details, please refer to the related link.

2025-06-12

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RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) is an international research center at RIKEN. It facilitates close collaborations among researchers from different disciplines in theoretical, mathematical and computational sciences. On April 1, 2025, iTHEMS transitioned from a program to a center. The ultimate goal of iTHEMS is to unravel the mystery of the Universe, matter, and life, as well as to solve key problems in modern society through interdisciplinary approaches.

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Director: Satoshi Iso

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Chang Po-Yao

Assistant Professor, Department of Physics, National Tsing Hua University, Taiwan

Term: June 30 (Mon) - August 24 (Sun), 2025

Visiting Place: Main Research Building
Nancy Bird

Research Fellow, University College London, UK

Term: July 27 (Sun) - August 1 (Fri), 2025

Visiting Place: Main Research Building
Alba Nieto Heredia

Ph.D. Student, L'Institut de Systématique, Évolution, Biodiversité, France

Term: July 28 (Mon) - August 9 (Sat), 2025

Visiting Place: RIKEN Wako Campus