RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences

Tracing the Origin of the “Freely Chosen Numbers” Appearing in the Laws of Nature

An international research team including Yuya Kusuki, Visiting Scientist at iTHEMS (Associate Professor, Institute for Advanced Study, Kyushu University), analyzed a situation in which two conformal field theories are connected through an interface. The researchers showed that, by appropriately extracting the response to a small deformation of the interface, one can obtain a local operator that captures the difference between the two theories. They also provided an explicit method for constructing such operators. This result lends support to the conjecture that quantum gravity does not admit continuous parameters that can be freely chosen from the outside, and is expected to contribute to a deeper understanding of fundamental issues in quantum gravity. For further details, please see the press release from Kyushu University.

2026-06-24

The First RIKEN Quantum International Workshop on Frontiers of Quantum Computing Applications and Quantum-HPC Integration on May 25-26, 2026

The First RIKEN Quantum International Workshop on Frontiers of Quantum Computing Applications and Quantum–HPC Integration was held from May 25 to 26 at the Large Conference Room on the 2nd floor of the Administrative Headquarters, RIKEN Wako Campus. The workshop featured an entirely invited program, consisting of 13 plenary presentations (40 minutes each) and 9 highlight presentations (20 minutes each). The presentations covered a broad range of fields—including quantum chemistry, life sciences, condensed matter physics, atomic physics, and high-energy physics—with a primary focus on the theme of quantum–HPC hybrid integration. With more than 130 registered participants, each presentation was followed by lively and engaging discussions. Furthermore, the networking reception held on the evening of the first day was well-attended, fostering active interaction and collaboration among researchers from universities, national research institutes, and private industries. This workshop is expected to drive further advancements in quantum computing through quantum–HPC hybrid integration. Reported by Shinichiro Fujii

2026-06-11

Keiya Hirashima Receives the HPCI Software Award (Development Division Excellence Award)

Keiya Hirashima, Special Postdoctoral Researcher at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), has received the Excellence Award in the Development Division of the HPCI Software Award, presented by the HPCI Consortium. The HPCI Software Award recognizes young researchers and organizations that have made significant contributions to the advancement of computational science through the development and dissemination of useful software. The Development Division specifically honors software that has demonstrated outstanding value in large-scale computational science and related fields. Hirashima received the award for the development of ASURA-FDPS-ML, a galaxy simulation code that incorporates artificial intelligence technologies. The software combines numerical simulations of galaxy formation and evolution with machine learning techniques, aiming to improve the efficiency and capability of large-scale astrophysical simulations. This award recognizes the significance of integrating computational science and AI technologies to advance next-generation scientific computing. Congratulations, Keiya!

2026-06-03

Okuto Morikawa Receives the 21st Particle Physics Medal: Young Scientist Award

Okuto Morikawa, Special Postdoctoral Researcher at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), has been awarded the 21st Particle Physics Medal: Young Scientist Award (FY2026). This award is presented to young researchers who have made outstanding contributions to the field of theoretical particle physics. The award-winning paper established a unified framework based on the exact WKB method for analyzing resonant states, which play an important role in quantum mechanics and quantum field theory. By connecting several previously independent approaches, including Zel'dovich regularization, the complex-scaling method, and the rigged Hilbert space formulation, the work provides a unified perspective on the description of resonant states. The study further demonstrated the effectiveness of this framework through exactly solvable models and was highly recognized for offering new insights that bridge scattering theory, non-Hermitian quantum systems, and resurgence theory. This research advances the fundamental understanding of quantum theories involving resonant states and is expected to contribute to future studies of non-perturbative structures in more general quantum systems, quantum field theories, and quantum gravity. Congratulations, Okuto!

2026-06-03

Development and Safety Validation of a High-Performance Japanese Medical LLM

As part of NEDO’s project “Safety Verification and Demonstration for the Social Implementation of a Japanese Medical Domain-Specific LLM,” a collaborative research team comprising ten institutions, including the University of Tokyo, RIKEN, and Kyushu University, developed a high-performance Japanese large language model (LLM) designed to support administrative tasks in healthcare settings. In evaluations based on specialist medical examinations, the model achieved an accuracy of up to 90.8%, demonstrating performance comparable to state-of-the-art commercial LLMs. The project also conducted extensive safety assessments tailored to the characteristics of the Japanese healthcare system. Jun Seita, Team Director of the Medical Science Deep Learning Team at iTHEMS, also participated in the project and contributed to its research and development. For more details, please see the NEDO press release.

2026-06-02

Identifying Topological Superconductors from Fermi Surface Information

An international research group including Seishiro Ono, Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, iTHEMS (at the time of the research; currently Visiting Scientist, Division of Global Collaborations and Research Talent Development), has established a theoretical formula that determines the topological properties of superconductors from information on the “Fermi surface,” which describes the electronic states responsible for electrical conduction and superconductivity. These research results are expected to provide a foundation for efficiently searching for topological superconductors among a vast number of materials, thereby accelerating both theoretical predictions and experimental exploration of candidate materials. For more details, please see the RIKEN press release.

2026-05-26

Discovery of a New Phenomenon Where Translational Symmetry Can No Longer Be Restored

A research group consisting of Tsubasa Oishi and doctoral student Takuma Saito of the Yukawa Institute for Theoretical Physics, Kyoto University, and Hiromi Ebisu, Research Scientist at RIKEN, has revealed that in systems of arbitrary dimensions subject to the Lieb–Schultz–Mattis (LSM) constraint arising from the interplay between internal symmetry and translational symmetry, the operation known as gauging—which converts a global symmetry into a local one—causes the translational symmetry itself to transform into a non-invertible symmetry. For further details, please see the Kyoto University press release.

2026-05-25

Mayor Takeshi Sakamoto of Itabashi City Visits iTHEMS on May 14

On May 14, Takeshi Sakamoto, Mayor of Itabashi City, visited iTHEMS and met with Center Director Satoshi Iso. Mayor Sakamoto introduced Itabashi City’s initiatives and basic development plan, followed by Director Iso’s presentation on the vision and activities of iTHEMS. The mayor then toured the iTHEMS spaces on the 2nd to 4th floors of the east side of the Main Research Building, where he interacted with researchers engaged in active discussions. In addition, at the Memorial Archives Room, Mayor Sakamoto viewed valuable historical materials that are also connected to Itabashi City.

2026-05-18

Talk Event “Useless Science and Art vol.2” Held at the Museum of Contemporary Art Tokyo

As a related event to the exhibition MOT Collection: Mission∞Infinity – Space × Art × Quantum, currently being held at the Museum of Contemporary Art Tokyo, the talk event “Useless Science and Art vol.2: Prototyping ‘Useless’ Science and Art” took place on Wednesday, May 6, 2026. This event was organized in connection with Black Hole Recorder, a work inspired by quantum black hole theory. Researchers and creators gathered to discuss the new possibilities that can emerge from ideas that may initially appear “useless.” Approximately 110 people attended the event. During the talks, the speakers introduced the conceptual framework of Black Hole Recorder and the theoretical ideas behind its creation. Visitors were also able to experience part of the work through a listening session held at the venue. The speakers included Tetsuo Hatsuda (Team Director, Quantum Mathematical Science Team, RIKEN iTHEMS), Koji Hashimoto (Professor, Graduate School of Science, Kyoto University), Yoshihiro Kozuka (Creative Director, ADK Marketing Solutions), and Haruka Kodama (Experience Designer, ADK Marketing Solutions). From their respective professional perspectives, they exchanged ideas on collaborations between science and art. Professor Hashimoto also discussed his cross-disciplinary activities exploring the theme of “Quantum × Music,” including translating concepts from quantum physics into musical expression. This program was held as the second installment of an ongoing talk series. Following the first session, the discussion further explored the significance of initiatives that bridge academic research and creative practice. After the main event, a wrap-up talk featuring participating artists, creators, and researchers from the exhibition was also held, with the same members continuing the discussion.

2026-05-18

iTHEMS x academist Online Event "World of Mathematical Sciences 2026" on April 18, 2026

RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) held the online event “Exploring the World of Science through Mathematics 2026” on Saturday, April 18, 2026, in collaboration with academist Inc. The event featured a series of lectures spanning a wide range of scientific fields, all connected through the perspective of mathematical sciences. Junnosuke Koizumi, Osamu Fukushima, Muzi Hong, and Kenji Okubo each gave presentations in their respective areas of expertise. The talks incorporated concrete examples to facilitate understanding, and also included discussions with commentators as well as Q&A sessions with participants. In addition, during the lunch break, Honorary Research Scientist Shun-ichi Amari and iTHEMS Director Satoshi Iso led a special session titled “Intelligence and Learning in the Age of AI.” Through an interactive dialogue with practical examples, they discussed how AI is influencing human intellectual activity and transforming approaches to learning. According to the post-event survey, overall satisfaction with the event was high. While some participants commented that the presentations were “somewhat difficult,” many also described them as “easy to understand.” A total of 303 participants (528 cumulative attendees) joined the event, with the maximum number of simultaneous connections reaching 184.

2026-05-14

Black Hole Recorder at EXPO 2025: “Entangle Moment — [Quantum, Ocean, Space] × Art” Exhibition Movie, Expo 2025 Osaka, Kansai

Career Opportunities at RIKEN iTHEMS: Research Administrator and Administrative Support Staff

Interview with Physicist Yuta Sekino [Part Ⅱ]

Interview with Physicist Yuta Sekino [Part Ⅰ]

Interview with Mathematician Takashi Tsuboi [Part Ⅲ]

Next-Generation Researcher Award 2024” Commemorative Interview (3): Keiya Hirashima, RIKEN iTHEMS

Next-Generation Researcher Award 2024” Commemorative Interview (3): Accelerating High-Resolution Galaxy Formation Simulations Using AI Surrogate Models (Takaya Hirashima, RIKEN iTHEMS)

Physicists’ Dialogue: Discussing Quantum Gravity and Black Holes — PART Ⅱ (in Japanese)

Physicists’ Dialogue: Discussing Quantum Gravity and Black Holes — PART Ⅰ (in Japanese)

Interview with Mathematician Taketo Sano [PART Ⅱ] (in Japanese)

Physicists’ Dialogue: Discussing Quantum Gravity and Black Holes — Digest (in Japanese)

Introduction to “Black Hole Recorder” (in Japanese)

Interview with Mathematician Taketo Sano [PART I]

A Century of Quantum Mechanics

Interview with Mathematician Takashi Tsuboi [Part Ⅱ]

Interview with Physicist Yasunori Nomura - Part Ⅳ

Interview with Physicist Yasunori Nomura - Part Ⅲ

Interview with Mathematician Takashi Tsuboi [Part Ⅰ]

Interview with Mathematician Yuto Moriwaki [Part2]

Interview with Mathematician Yuto Moriwaki [Part 1]

Interview with Mathematician Eiji Inoue [Part 2] (in Japanese)

Interview with Physicist Yasunori Nomura - Part Ⅱ

The Connection Between Mathematics and Microbial Research: From Fisheries Science to the Path of Mathematics

Contributed to the 'One Poster per Household' Project – Like the Ones You See in Science Classrooms

Interview with Dr. Misako Tatsuma, a Planetary Formation Theorist

Interview with Mathematician Eiji Inoue [Part 1]

Interview with Physicist Yasunori Nomura - Part I

Interview with Physicist Ryo Namba [Part 2]

Interview with Physicist Ryo Namba [Part 1]

Interview with Ryosuke Iritani, Mathematical Biologist [Part 1]

Theoretical Physicist Tetsuo Hatsuda Interview Vol.2: About Research and Mathematics

Theoretical Physicist Tetsuo Hatsuda Interview Vol.1: About RIKEN iTHEMS

What about climate change in actuality?

An Introduction to TQFTs (from a Mathematician’s Viewpoint)

But how many baskets should you put your eggs in?

Spontaneous symmetry breaking

The transition to synchronization: from phase reduction to the Kuramoto model

What Are Modular Forms?

Brunn-Minkowski inequality and the Borell-Brascamp-Lieb inequality

Aspects of Quantum Resonance Revisited

Distances and Durations: Cosmology 101

Symmetries of gravity

Birational classification of algebraic varieties

Gelfand duality

Scale transformations in physics and beyond

Machine Learning for Holographic Entanglement Inequalities

Describing Quantum Phenomena with Classical Gravity

Statistical Signatures of Quantum Chaos in Non-Hermitian Systems

Computers as a Playground for Mathematics

The Free Will Theorem in Quantum Mechanics

Renormalization revisited

Renormalization: Awareness of Ignorance

Recipe for soup of quarks and gluons

A subjective view on what is a quantum effect

Mathematical aspects of the entropic uncertainty relation

Forming black holes from stars

Singularity Theorems

Resurgence: making sense out of non-convergent series

How can we use a quantum computer to study the ground state of the hydrogen molecule?

Applications and Extensions of the Nielsen-Ninomiya Theorem in Condensed Matter Physics

COVID-19: then, now, and into the future

Exploring Quantum Spacetime

Classical simulations of quantum computers

When a Cretan says all Cretans are liars

Physical and local observables in gravitational theory

Can you hear the shape of a drum?

Quantum many-body physics with cold atoms

complexity in non-unitary dynamics of photons

Physics Through the Looking Glass

A new B.O.A.T. in astrophysics

Evolution and our daily rhythms

Area law of entanglement entropy in quantum many body systems and its implication in tensor network calculation

Comparison between conventional computers and quantum computers

A glimpse of enumerative geometry

Message-passing algorithms for graphical models

Canonical form of tensor networks in one and two dimensions

The basics of topological band theory

Building something from nothing: a mathematical framework for aperiodic/amorphous sets

Planetary lightning: Current State-of-the-art and outstanding questions

Collective Power of Science ~ from the High-Energy Atmospheric Physics to our New Exploration of the Universe ~

Morse theory and Floer theory

Knot theory and topological semimetals

On Dark Matter

Odd couples of interdisciplinary research

Khovanov homology theory - an introduction to categorification by Dr. Taketo Sano on May 13, 2022

Fundamentals Fest, mini Pre-event on Science "Exploring and Bridging: The Potential of Basic Science"

In Search of Pc pentaquark - Simulate Hadron Interactions with FUGAKU

AAS Journal Author Series: Hirotaka Ito on 2021ApJ…918...59I

Will Useless Knowledge Change the Future? - What is the Black Hole Recorder?

RIKEN 2019 (in Japanese)