RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences

Masason Foundation Summer Program Visit to the RIKEN–Berkeley Center on August 11, 2026

Participants in the Masason Foundation’s summer program visited the RIKEN–Berkeley Center at the University of California, Berkeley, on August 11, 2026. The summer program provides young participants with opportunities to broaden their perspectives through visits to universities, research institutions, and other organizations, and through direct interactions with researchers and professionals. The visit began with a tour of the UC Berkeley Physics Department, including an introduction to its history and research environment. This was followed by short presentations by researchers, including Shoto Aoki, Yuka Kanakubo, Gabriele Di Ubaldo, and Akira Dohi, who introduced their research activities to the participants. In the latter part of the program, the participants visited several experimental laboratories at UC Berkeley. Through the presentations, discussions, and laboratory visits, they had an opportunity to learn about a broad range of research activities and to experience firsthand the environment in which cutting-edge research is carried out. The visit provided a valuable opportunity for the young participants to interact directly with researchers at RIKEN and UC Berkeley and to gain a broader perspective on scientific research and possible future career paths. Reported by Shuntaro Aoki

2026-09-08

From Vietnam to Korea: A Summer of Quantum Computing

Duc-Truyen Le, a graduate student at Saitama University, is currently affiliated with iTHEMS as an International Program Associate (IPA). This summer, he participated in a series of quantum computing activities in Vietnam and Korea. In Vietnam, his team received an Honorable Mention at an international quantum computing hackathon involving participants from across Southeast Asia. We asked Duc-Truyen to share his experience with the iTHEMS community: From July 9 to 31, I stayed in Vietnam, mainly to prepare for and participate in a major quantum computing event that brought together scientists, industry leaders, policymakers, and government representatives. The event aimed to strengthen collaboration and promote investment in quantum technologies across both the public and private sectors. The program consisted of a series of activities held over more than a week, including workshops, discussions, networking events, and competitions. One of the highlights was the International Hackathon on Quantum Computing for Social Good (QC4SG Vietnam 2026 / 2nd SEA Quantathon), which brought together participants from across Southeast Asia. The competition was highly selective, with more than 500 initial applications. Selected teams went through a training phase before the finalists were invited to Vietnam to present their projects. For more information about the competition, please see the related link below. Among more than 20 finalist teams, comprising around 100 participants, our team, QuanWatt, was honored to receive an Honorable Mention. It was a rewarding experience and a valuable opportunity to exchange ideas with participants from different backgrounds. Our project explored how quantum computing could contribute to the analysis of modern power systems, which are becoming increasingly complex with the growing integration of renewable energy sources and smart-grid technologies. Although considerable work remains before such approaches can be applied in practice, it was encouraging to see increasing interest from both academia and industry in practical applications of quantum computing. Following the program in Vietnam, I traveled to Korea, where I attended a course at the Institute for Basic Science (IBS) from August 1 to 8 on “Quantum Computing for Quantum Field Theory.” This provided another valuable opportunity to learn about the rapidly developing connections between quantum computing and fundamental physics. Overall, these experiences in Vietnam and Korea were both memorable and intellectually stimulating. I am very grateful for the opportunity to participate and for the continued support I have received from iTHEMS.

2026-09-01

The 3rd NCTS-iTHEMS Joint Workshop on Theoretical, Mathematical, and Computational Sciences on August 18, 2026

The 3rd NCTS-iTHEMS Joint Workshop on Theoretical, Mathematical, and Computational Sciences was held from August 18 to 21, 2026, at the NCTS Physics Lecture Hall in the Cosmology Hall of National Taiwan University (NTU), Taipei. This was the third workshop in the series jointly organized by Taiwan's National Center for Theoretical Sciences (NCTS) and RIKEN iTHEMS, following the first workshop hosted by NCTS in 2024 and the second hosted by RIKEN in 2025. This year's workshop carried special significance as the first major joint activity after the signing ceremony held at NTU on April 23, 2026, where iTHEMS and NCTS launched the joint research initiative "Mathematical Frontiers for Matter, Life, and the Universe." The initiative, signed by iTHEMS Director Satoshi Iso and NCTS Directors Pei-Ming Ho and Ming-Lun Hsieh, aims to foster outstanding early-career researchers and to promote researcher exchanges, international symposia, and collaborative research between the two institutions. Reflecting this spirit, the scope of the workshop expanded beyond previous editions to encompass theoretical physics, mathematics, and computational sciences. The four-day program featured 28 talks and 10 posters. Three plenary lectures were delivered by Tzu-Chieh Wei (Stony Brook University) on the stability of quantum many-body phases against time-dependent perturbations, Etera Livine (ENS Lyon) on spinfoam approaches to quantum gravity, and Tan Bui-Thanh (UT Austin) on model-constrained scientific machine learning for digital twins. Thirteen invited speakers from RIKEN iTHEMS and twelve from Taiwanese universities and Academia Sinica presented research spanning high-energy physics, gravity, condensed matter physics, quantum information and computing, geometry and topology, applied mathematics, machine learning, and scientific AI. In the poster session, ten presenters, mostly students and early-career researchers, introduced their work in three-minute flash talks followed by lively discussions over coffee. The directors of both institutions delivered the opening and closing remarks, and the iTHEMS and NCTS organizers held internal discussions on future joint activities during the workshop. The interdisciplinary atmosphere led to many cross-field conversations during the coffee breaks, the poster session, and the banquet, and several new contacts between researchers of the two institutions were established. We thank the NCTS staff for their excellent local organization and all speakers and participants for making the workshop a success. We look forward to continuing the series and to deepening the collaboration between NCTS and iTHEMS under the new initiative. Reported by Ching-Kai Chiu

2026-08-31

New Mechanism for Sustaining Reputation-Based Cooperation Revealed

An international research team including iTHEMS Team Director Yohsuke Murase has theoretically uncovered a new mechanism that enables the evolution of reputation-based cooperation. In human societies, “indirect reciprocity,” in which people decide whether to cooperate with others based on their reputations, is considered an important mechanism for sustaining cooperation. However, previous studies have shown that maintaining cooperation becomes difficult when individuals hold different assessments of the same person. In this study, the researchers introduced a mechanism called “dual reputation updating,” in which reputations are updated based not only on whether a person cooperates with others, but also on whether that person receives cooperation from others. Through mathematical analysis and computer simulations, they demonstrated that this simple extension reduces disagreements in reputation and substantially enhances the maintenance of cooperation. These findings are expected to deepen our understanding of how cooperation emerges and is sustained through reputation, while also providing new insights into collective behaviors in real-world societies, including conformity, cooperation, and exclusion. The findings are scheduled to be published in the Proceedings of the National Academy of Sciences (PNAS) on August 28, 2026.

2026-08-25

Farewell message from Sungsik Kong

Our colleague, Sungsik Kong, will be joining Sejong University in South Korea as a tenure-track Assistant Professor in September 2026. We will all miss him and wish him every success in this exciting new chapter. Here is a message from Sungsik: <i>I joined iTHEMS in August 2025, and over the past year I have had the privilege of working in an exceptional research environment. Starting in September 2026, I will be joining Sejong University in South Korea as a tenure-track Assistant Professor. While I am excited about this move, I am also sad to be leaving my position as a Research Scientist at iTHEMS.</i> <i>My time at RIKEN has been both challenging and incredibly rewarding. I am deeply grateful to RIKEN and iTHEMS for giving me the opportunity to pursue the scientific questions I am passionate about. I will miss iTHEMS' collaborative atmosphere. I have had the chance to learn from researchers across many different fields, many that I would never have had the opportunity to explore otherwise. Those seminars, colloquiums, and conversations have broadened my perspective, sparked new ideas, and made my time here truly valuable and memorable.</i> <i>If you ever visit Seoul, please don't hesitate to get in touch. Thank you all so much. It has been a real pleasure.</i>

2026-08-17

Using chaos and symmetry to bootstrap quantum gravitational wormholes

An international research collaboration between Gabriele Di Ubaldo (RIKEN-Berkeley Center at UC Berkeley and RIKEN iTHEMS), Jan Boruch (University of California, Berkeley, US), Felix M. Haehl (University of Southampton, UK), Eric Perlmutter (Université Paris-Saclay and Institut des Hautes Études Scientifiques, France), and Moshe Rozali (University of British Columbia, Canada) published the new study in <em>Physical Review Letters</em>. Random matrix theory provides a universal description of chaos in quantum systems, capturing statistical patterns among energy levels without requiring knowledge of microscopic details. The new challenge addressed is its extension to 2D Conformal Field Theories and their holographically dual 3D quantum gravity via the AdS₃/CFT₂ correspondence. In the AdS₃/CFT₂ correspondence, quantum gravity in a three-dimensional negatively curved spacetime is encoded in a two-dimensional conformal field theory on its boundary. The key difference is <strong>modular invariance</strong>, a symmetry stating that a theory on a 2D torus is invariant under modular transformations, which imposes stringent constraints and a rigid mathematical structure, seemingly incompatible with quantum chaos and random matrix theory. Building on the 2023 work of Di Ubaldo and Perlmutter, “AdS₃/RMT₂ duality”, the researchers developed a general, nonperturbative framework called RMT₂ that uplifts the correlations of any random matrix model into fully modular-invariant quantities. The team then used RMT₂ to predict quantum amplitudes for 3D wormholes with multiple torus-shaped boundaries. A wormhole is a tunnel-like geometric connection between otherwise separate regions or boundaries of spacetime. While it is not a shortcut for interstellar travel as in sci-fi movies, it encodes deeply quantum information about gravity and black holes. For the three-boundary wormhole, the team also performed a gravity calculation that agrees with the RMT₂ prediction. By turning the earlier AdS₃/RMT₂ proposal into a general framework, the study advances a research direction that Gabriele helped pioneer and provides a new tool for probing black-hole microstates and, in the near future, solving AdS₃ quantum gravity. For further details, please see the article in <em>Physical Review Letters</em>.

2026-08-07

Riccardo Muolo Awarded Third Place at Falling Walls Lab Tokyo 2026

Riccardo Muolo awarded 3rd Place at Falling Walls Lab Tokyo, Japan Riccardo Muolo (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, iTHEMS) took part in the Falling Walls Lab Tokyo, Japan, held on 28 July 2026 at Shibuya Sakura Stage, and was awarded 3rd Place by the jury. The Falling Walls Lab is an international pitch and science-communication competition hosted by the Falling Walls Foundation, a Berlin-based non-profit founded in 2009 on the twentieth anniversary of the fall of the Berlin Wall. The Foundation channels the spirit of that night to ask a recurring question — which are the next walls to fall in science and society — and works to make breakthrough ideas accessible across borders and disciplines. Open to students and early-career professionals of all disciplines and nationalities, the Lab invites participants to pitch their research, business model, or innovative idea in just three minutes, in front of their peers and a jury from academia and business. Academic institutions around the world are invited to host their own Falling Walls Lab and send their winners to the Falling Walls Lab Finale in Berlin, where the Finalists compete for the title of Breakthrough Winner in the Emerging Talents category and the chance to pitch again on the main stage of the Falling Walls Science Summit. This year’s Tokyo edition was organized by EURAXESS Japan, the German Centre for Research and Innovation (DWIH) Tokyo, and Tobitate! Japan. Riccardo’s research covers nonlinear dynamics on networks and higher-order structures, synchronization, Turing pattern formation, and the control of dynamical systems — exactly the kind of cross-disciplinary work the Falling Walls Lab is designed to showcase. Distilling it into a compelling three-minute pitch and earning recognition among a strong international field of participants is a fine achievement. Congratulations, Riccardo!

2026-08-07

Discovery of Anomalous Fluctuations and Universality in Atom Detection Counts

Kazuki Yamamoto, Lecturer at the Graduate School of Science, Osaka Metropolitan University, and Ryusuke Hamazaki, RIKEN Hakubi Research Team Leader at the RIKEN Pioneering Research Institute and Senior Research Scientist at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), have theoretically demonstrated that the fluctuations in the number of detected atoms in a continuously measured quantum many-body system consisting of a large number of atoms change dramatically depending on the measurement strength. They found that when the measurement is weak, the number of detected atoms exhibits standard fluctuations, whereas when the measurement is strong, unusually large anomalous fluctuations emerge. For more details, please visit the Osaka Metropolitan University website.

2026-08-06

2026 iTHEMS Visit by the National Sun Yat-sen University, Taiwan

On June 25, a group of 3 professors and 13 students from National Sun Yat-sen University, Taiwan, visited RIKEN . The purpose of the visit was to immerse the students in RIKEN’s multidisciplinary research environment and introduce them to stateoftheart scientific methodologies. It also aimed to inspire their future research careers while exploring opportunities for academic exchange and longterm collaboration between both institutions. First, the group visited RIKEN Nishina Center for Accelerator-Based Science, hosted by Dr Claudio Santonastaso & Dr Seiya Sakai. Next visit was RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), hosted by Dr. Gen Kurosawa. Last visit was RIKEN Center for Quantum Computing, hosted by Dr. Franco Nori. Gen Kurosawa, Senior Research Scientist, introduced iTHEMS’s interdisciplinary research environment and explained how mathematical methods from physics can be applied to important questions in biological clocks, leading to testable predictions that are verified experimentally.

2026-07-29

Farewell message from Puttarak Jai-akson

Our colleague, Puttarak Jai-akson, will be joining the Graduate School of Science, Kyoto University, as a Program-Specific Researcher, starting in August 2026. We will all miss him and wish him every success in this exciting new chapter. Here is a message from Puttarak: <i>I would like to share that I will be leaving my position as a Postdoctoral Researcher at iTHEMS.</i> <i>I joined iTHEMS in November 2022, and after nearly four wonderful years, I will be moving to a new position as a Researcher at Kyoto University, starting in August 2026.</i> <i>During my time at iTHEMS, I greatly enjoyed the open, friendly, and interdisciplinary research environment. The opportunity to interact with researchers from diverse fields has broadened my perspective, inspired many new ideas, and significantly enriched my research. I am deeply grateful to all the members of iTHEMS for their support, encouragement, and the many enjoyable discussions we have shared. I would also like to express my heartfelt thanks to our wonderful iTHEMS Assistants, whose kindness, professionalism, and constant support made my time at iTHEMS all the more enjoyable.</i> <i>Although I am leaving my full-time position, I am pleased to continue my affiliation with iTHEMS as a Visiting Scientist. I sincerely hope to continue our discussions and collaborations in the future.</i> <i>If you happen to visit Kyoto University, please don't hesitate to let me know. I would be very happy to catch up and continue our conversations.</i> <i>Thank you all very much for everything. It has been a privilege to be part of iTHEMS, and I wish everyone continued success.</i>

2026-07-24

Interview with Mathematician Motoko Kotani [Part I]

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?

Maxwell’s Demon in Biology: The Cost of Using Information

Heun Functions as a Common Language: Black Holes Meet Gauge Theory

God saves quantum computers by playing dice: introduction to quantum error correction

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)