RIKEN Interdisciplinary Theoretical and
Mathematical Sciences Program

The Story of the "Discovery" of Numbers

Author: Hiroyasu Miyazaki Language: Japanese Release date: March 25, 2025

2025-03-27

Farewell message from Akihisa Yamamoto

Our colleague, Akihosa Yamamoto, will be joining Department of Mechanical Systems Engineering, Faculty of Systems Design at Tokyo Metropolitan University as an Associate Professor starting April 1st, 2025. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Akihisa: <i>I joined RIKEN iTHEMS as a research scientist in April 2024. Although it has only been a year, I truly enjoyed my time here. I have encountered many exciting and diverse research topics that have significantly expanded my scientific horizons and thoroughly enjoyed attending seminars across various fields. Due to the great diversity and high quality of the presentations, it has not always been easy to grasp the key take-home messages and formulate relevant questions. Nonetheless, I have always enjoyed the opportunity to immerse myself in these stimulating discussions. I am also very grateful for the positive atmosphere of iTHEMS, fostered by talented and considerate colleagues. It has been a great pleasure to be a part of this fantastic institute, and I sincerely thank the Program Director Hatsuda-san and every member of iTHEMS including all the assistants for collectively maintaining such a supportive environment. I will be appointed as an Associate Professor in the Biomechanical Engineering Area in the Department of Mechanical Systems Engineering, Faculty of Systems Design at Tokyo Metropolitan University on April 1st, 2025. I plan to continue my exploration of the mechanistic understanding of homeostasis and the dynamics of living systems. I am sure that the scientific perspective and thought processes I have developed during my time at iTHEMS will remain with me throughout my scientific career. I sincerely wish for the continuous and even greater success of iTHEMS, and I look forward to staying in touch with iTHEMS members.</i>

2025-03-24

Farewell message from Rongyang Sun

Our colleague, Rongyang Sun, will be joining Department of Physics and Astronomy, California State University Northridge, as a postdoctoral researcher, starting April 2025. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Rongyang: <i>I joined iTHEMS in April 2023 as part of RIKEN Quantum, and you may not even meet me on campus as my base is at R-CCS in Kobe. Although my time in iTHEMS has been short, formally only half a year, and I participated in the events remotely most of the time, I learned so much, far more than I expected, from this active research institute, which owns the best diversity and productivity. I would like to thank all the members of iTHEMS, including the directors, researchers, and assistants. Thank you for giving me such a unique experience in my research career!</i> <i>While I am moving to the US, a physically very far away place, I will continue to follow the development of iTHEMS and share in its success. Starting in April 2025, iTHEMS will be upgraded to a research center. I sincerely wish all the members and the institute greater success in this new era!</i>

2025-03-23

Farewell message from Steffen Backes

Our colleague, Steffen Backes, will be joining the RIKEN TRIP Research DX Team as an Expert Technician, starting April 1, 2025. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Steffen: <i>I joined iTHEMS and RIKEN in August 2023, so only about 1.5 years ago, but this time had a lasting impression on my personal life and scientific career. It is hard to overstate how much I enjoyed being part of iTHEMS, as it has been an incredibly enjoyable and rewarding time. Being able to meet so many knowledgeable and kind people from different fields and parts of the world, and coming up with new and unconventional ideas due to different backgrounds, was truly amazing. I am very grateful for having been accepted to iTHEMS, which I think is a very special and outstanding place due to this diversity and scientific freedom, that is hard to be found elsewhere. </i> <i>In FY2025 (April 1st) I will change to an Expert Technician position in the RIKEN TRIP Research DX Team, Wako Campus, so I will still stay close to iTHEMS! As far as time allows, I will make sure to drop by and say hello :) Thank you everyone for this great time, and let's meet again soon!</i>

2025-03-18

Farewell message from Jizhou Li

Our colleague, Jizhou Li, will be joining Professor Akira Shudo's group in the Department of Physics at Tokyo Metropolitan University as a postdoctoral researcher, starting April 1, 2025. We will all miss him and wish him the best of luck in this new endeavor. Here is a message from Jizhou: <i>As I move on to my next position at Tokyo Metropolitan University, I just wanted to say a big thank you to all of you. I’ve really enjoyed the discussions, collaborations, and all the insightful talks at iTHEMS. The biology seminars and coffee meetings, in particular, have been a fantastic learning experience for me.</i> <i>Luckily, since I live just 1 km from RIKEN, I’m not going too far! I still plan to drop by for the biology seminar every Thursday, so I’m looking forward to more chats and discussions with you all.</i> <i>Thanks again, and see you around!</i>

2025-03-12

Review on Physics-Driven Learning for Inverse Problems Published in Nature Reviews Physics

Nature Reviews Physics recently published a review paper on ”Physics-driven learning for inverse problems in quantum chromodynamics”, from DEEP-IN working group led by Lingxiao Wang (Research Scientist, iTHEMS), including Tetsuo Hatsuda (Program Director, iTHEMS). The authors explore how combining deep learning techniques with physics-driven designs significantly improves the extraction of accurate physical properties from complex QCD phenomena. Highlighting applications such as lattice QCD calculations and studies of hadron interactions, neutron stars, and heavy-ion collisions, the review emphasizes the benefits of embedding physical priors into machine learning models and suggests broader potentials to general physics problems.

2025-03-06

RIKEN-Nara Women's University Joint Diversity Promotion Workshop 2025 on March 3, 2025

On March 3 and 4, a total of 19 students from various courses at Nara Women's University—including mathematics, physics, chemistry, biological sciences, and environmental sciences (comprising first-year, second-year, and third-year undergraduate students, as well as first-year master's students)—visited RIKEN. During their visit, they toured several research facilities, including the RIBF Facility at the RIKEN Nishina Center (RNC), the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), the Laboratory for Sensorimotor Integration at the RIKEN Center for Brain Science (CBS), the Photonics Control Technology Team at the RIKEN Center for Advanced Photonics (RAP), and the Molecular Bioregulation Research Team at the RIKEN Center for Sustainable Resource Science (CSRS). At each laboratory, the students had the opportunity to engage with cutting-edge research up close, observe experimental equipment, and ask researchers about their work. In the evening, they participated in a networking session with RIKEN researchers, where they explored research topics in depth through iTHEMS members' poster presentations. This interactive session also provided insights into the daily lives and career paths of researchers, offering students valuable inspiration from the research environment. This diversity promotion initiative is a collaborative project between the Faculty of Science at Nara Women's University and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), conducted under the auspices of the RIKEN Diversity Promotion Office. It is organized alongside a series of lectures at Nara Women's University and is planned to continue in the coming years.

2025-03-06

Farewell message from Jeffrey Fawcett

Our colleague, Jeffrey Fawcett will move on to a new career as a Chief Scientist at Regional Fish Institute, Ltd. as of March 1st, 2025. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Jeffrey Fawcett: <i>I will be moving to Kyoto to work at a company called Regional Fish from March. I will also most likely have a joint position at Kyoto University at a lab funded by the company. The company was started a few years ago mostly be people from Kyoto University, Graduate School of Agriculture, where I did my study, and specializes in breeding and developing fish and aquatic species using genome editing and various other techniques. My task will mainly be to perform genomic data analysis for the company, although I will also have some freedom to pursue my own research. I am looking forward to the new challenge to utilize my expertise and work for a company whose I mission I can identify with.</i> <i>I have been in iTHEMS for exactly 7 years, which say how much I enjoyed and appreciated the setup of iTHEMS. I remember some people telling me its their first time meeting a biologist, whereas I never imagined I would ever have the opportunity to enjoy talks on pure mathematics and theoretical physics. I would like to thank all the people involved in iTHEMS and hopefully I will be able to visit iTHEMS from time to time and keep up the connection.</i>

2025-02-25

Who Is at Higher Risk of Progression from Acute Liver Injury to Acute Liver Failure?

A collaborative research group, including Professor Shingo Iwami (Visiting Scientist, iTHEMS / Professor, Graduate School of Science, Nagoya University), has applied artificial intelligence (AI) technology to clinical research. Through joint research, they discovered that patients with acute liver injury can be classified into three groups based on their treatment response. Furthermore, they successfully developed the world's first AI model capable of predicting which group a patient belongs to using clinical data such as initial blood test results. For more details, please visit Kyushu University’s website via the related links.

2025-02-10

Make it worth Weyl: engineering the first semimetallic Weyl quantum crystal

An international research team, including Ching-Kai Chiu (Senior Research Scientist, iTHEMS) and led by the Strong Correlation Quantum Transport Laboratory of the RIKEN Center for Emergent Matter Science (CEMS) has achieved a world-first by realizing an ideal Weyl semimetal, marking a major breakthrough in quantum materials research. Weyl fermions emerge as quantum excitations of electrons in crystals and are predicted to exhibit exotic electromagnetic properties. However, previous Weyl materials were often overshadowed by unwanted electronic states, making it difficult to observe pure Weyl fermion behavior. The team successfully engineered an ideal Weyl semimetal by precisely controlling the composition of the topological semiconductor (Cr,Bi)₂Te₃, eliminating irrelevant electronic states. Published in Nature, this work opens new possibilities for terahertz (THz) light devices and next-generation electronics. For more details, please refer to the related link.

2025-01-29

 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?

 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