iTHEMS Cosmology Forum n°6 - Cosmological Collider Physics

June 22 (Mon) 9:15 - 17:00, 2026

Yi Wang (Professor, Department of Physics, Hong Kong University of Science and Technology, Hong Kong)
Masahide Yamaguchi (Director, Center for Theoretical Physics of the Universe, Institute for Basic Science, Republic of Korea)
Kyohei Mukaida (Assistant Professor, Theory Center, High Energy Accelerator Research Organization (KEK))
Kazuyuki Akitsu (R&D, Proxima Technology)

This sixth workshop will bring together researchers exploring the physics of the early universe through cosmological collider signatures. Primordial non-Gaussianities generated during inflation provide a unique opportunity to probe heavy particles and high-energy interactions in the early universe, potentially accessing energies much larger than that probed by terrestrial experiments. In recent years, the subject has developed rapidly, incorporating ideas from inflationary cosmology, quantum field theory in curved spacetime, effective field theory, and scattering amplitudes.

Venue: Okochi Hall

Event Official Language: English

Gravitational Properties of the Monopole Bag

June 23 (Tue) 13:30 - 15:30, 2026

Yu Komiya (Ph.D. Student, Yukawa Institute for Theoretical Physics, Kyoto University)

Processes such as phase transitions and symmetry breaking in the early universe are well-studied and thought to be instrumental in giving rise to the nature and composition that we observe. In particular, axionic cosmologies constitute a class of phenomenologically rich models with symmetry breaking, UV relevance, and potentially detectable consequences. In the case where monopoles are also present in such a background, the axion profile may be deformed; it is possible to construct a "monopole bag" state composed of a central monopole within a closed axion domain wall. We consider the gravitational properties of this hybrid defect, and find a both horizon-less and a black hole-like final state can result as remnants of the monopole-domain wall system after gravitational collapse for different input parameters

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Lectures on Quantum Measurement Theory: III

June 23 (Tue) 15:30 - 17:00, 2026

Masanao Ozawa (Professor Emeritus, Nagoya University)

Lecture III: Measurement error, disturbance, the universally valid reformulation of Heisenberg’s uncertainty principle, and a quantitative generalization of the Wigner–Araki–Yanase theorem Definitions of measurement error and disturbance are introduced (Ozawa 2002, 2019) and it is shown that there exists a solvable model for a physically realizable measurement that serves as a counterexample both to Heisenberg’s uncertainty principle in the conventional formulation and to the SQL (Ozawa 1988, 1989, 2002). Thus, those limits are no more considered as universal limits. In fact, the above counter example to SQL was found in 1988 using the idea of contractive state measurements by Yuen (1983) and the LIGO was started in 1994 to succeed in the gravitational wave detection in 2015 as announced in 2016. New formulations are then proved for the uncertainty principle concerning the errors in the approximate simultaneous measurement of two physical quantities, called the "joint error relation" (Ozawa 2003b, 2004), and for the uncertainty principle concerning the error and disturbance associated with the measurement of a single physical quantity, called the "error-disturbance relation" (Ozawa 2003a). From the error-disturbance relation, a quantitative relation for measurement error under an additive conservation law is proved (Ozawa 2002a, 2003b), generalizing the "Wigner–Araki–Yanase theorem" (Wigner 1952, Araki-Yanase 1960), which states that a physical quantity not commuting with a conserved quantity cannot be measured accurately by a measurement interaction satisfying an additive conservation law. The above relation also derives limits for realizing quantum computing and operations under conservation laws (Ozawa 2002b), the results later developed as the resource theory of asymmetry.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Machine-learned fixed-point actions and observables for SU(3) lattice gauge theory

June 24 (Wed) 10:30 - 11:30, 2026

Müller David (Postdoc, Institute for Theoretical Physics, TU Wien, Austria)

Lattice regularization is the established approach for studying non-perturbative phenomena in quantum chromodynamics, but accurate predictions for the continuum theory remain challenging because standard actions exhibit large lattice artifacts. The renormalization group on the lattice provides a way of suppressing these artifacts: classically perfect fixed-point (FP) actions. In this talk, I show how gauge-equivariant neural networks yield accurate parametrizations of FP actions. Using these machine-learned actions, we perform Monte Carlo simulations to measure gradient-flow scales with highly suppressed artifacts compared to unimproved actions. I will also present preliminary results for machine-learned FP observables to improve the extraction of the topological susceptibility in four-dimensional SU(3) gauge theory.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Fermionic modes of D-instanton wormholes from broken local supersymmetry

June 24 (Wed) 15:30 - 17:00, 2026

Hiroshi Itoyama (Specially Appointed Professor, Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), Osaka Metropolitan University)

In low-energy supergravity treatment of type IIB superstring on general D-instanton wormhole profiles in the bulk, we obtain non-vanishing scalar two-point functions in addition to the vanishing　〈τ＊τ＊〉 that corresponds to the BPS amplitude detected by two D-instantons at their respective boundaries. This is exploited to show that the modes of broken local supersymmetry in the bulk deliver the fermionic (diagonal) modes on the boundaries through the deformation by the form of current-current two point functions propagating on the tree level cylinder geometry. Our treatment is generalizable to multi D-instanton cases and general Euclidean branes.

Venue: #359, 3F, Main Research Building (Main Venue) / via Zoom

Event Official Language: English

Classical and quantum computing of Nash equilibria of two-player games

June 25 (Thu) 10:30 - 11:30, 2026

Erik Loetstedt (Senior Research Scientist, Quantum Mathematical Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Nash equilibrium is an important concept in game theory. However, finding mixed-strategy Nash equilibria is computationally hard even for relatively small games. I will review some aspects of the numerical computation of Nash equilibria of two-player games including the Lemke-Howson algorithm. I will also discuss preliminary attempts at solving the Nash equilibrium problem on a quantum computer by the quantum approximate optimization algorithm.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Mathematical Application Research Team Meeting #16

June 26 (Fri) 10:30 - 12:00, 2026

Yuichi Ike (Associate Professor, Graduate School of Mathematical Sciences, The University of Tokyo)

Mathematical Application Research Team is honored to invite Prof. Yuichi Ike from the University of Tokyo to this meeting. Everyone is welcome to join the meeting to listen to his seminar. Title: Persistent Homology: Theory and Applications Abstract: Persistent homology is one of the main tools in topological data analysis (TDA), encoding the topological features of given data into persistence diagrams, which are multisets in two-dimensional space. It has been successfully applied to various fields such as materials science and computer graphics. In this talk, I will provide an overview of persistent homology from both theoretical and practical viewpoints. I would also like to discuss persistent-homology-based loss functions, which can be used to control the topological structure of parameters in machine learning.

Venue: #359, 3F, Main Research Building (Main Venue) / via Zoom

Event Official Language: English

Symmetry origin of the quantum-classical transition, hydrodynamics, and decodability.

June 26 (Fri) 14:00 - 16:00, 2026

Cenke Xu (Professor, University of California, Santa Barbara, USA)

We discuss the following question: when a quantum system evolves into classical one, is there a sharp transition? We will show that the “strong-to-weak” spontaneous symmetry breaking (SW-SSB) provides a sharp onset of classical physics. We present the theoretical framework and summarize recent experimental progress toward observing SW-SSB. We will also discuss the consequence of the SW-SSB, including the emergence of hydrodynamics, and also its information aspect, such as the transition of decodability and distinguishability. Much of the theoretical analysis maps to a problem of defect in the Euclidean spacetime.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Primitive Ideals and Hilbert Space Representations of Quantized Coordinate Algebras of Complex Semisimple Lie Groups

June 26 (Fri) 16:30 - 18:00, 2026

Heon Lee (Postdoc Researcher, Institute for Advanced Study in Mathematics, Harbin Institute of Technology, Republic of Korea)

The primitive ideals of the coordinate algebra $ \mathcal{O} ( G ) $ of a complex semisimple Lie group $ G $ are in bijection with the points of $ G $, via the correspondence assigning to each point of $ G $ the kernel of the associated evaluation homomorphism on $ \mathcal{O} ( G ) $. This establishes a direct link between the algebraic structure of $ \mathcal{O} ( G ) $ and the geometry of $ G $. In this talk, we investigate the quantum analogue of this classical relationship for the $ q $-deformation $ G_q $. Specifically, we establish a sharp dichotomy: primitive ideals in homogeneous Joseph strata arise as kernels of irreducible representations of $ \mathcal{O} ( G_q ) $ by bounded operators on Hilbert spaces, which provide a quantum analogue of evaluation homomorphisms at points of $ G $, whereas those in inhomogeneous Joseph strata do not. This clarifies the extent to which the primitive spectrum of $ \mathcal{O} ( G_q ) $ can be accessed through operator-theoretic methods. We also analyze the semiclassical consequences of this result in light of the fact that the primitive ideals of $ \mathcal{O} ( G_q ) $ are parametrized by the symplectic leaves of the natural Poisson structure on $ G $. This talk is based on joint work with Christian Voigt.

Venue: via Zoom / Seminar Room #359

Event Official Language: English

Phase Transitions as the Breakdown of Statistical Indistinguishability

June 29 (Mon) 15:00 - 16:00, 2026

Hideyuki Miyahara (Associate Professor, Graduate School of Information Science and Technology, Hokkaido University)

We introduce a novel characterization of phase transitions based on hypothesis testing. In our formulation, a phase transition is defined as the breakdown of statistical indistinguishability under vanishing parameter perturbations in the thermodynamic limit. This perspective provides a general, order-parameter-free framework that does not rely on model-specific insights or learning procedures. We show that conventional approaches, such as those based on the Binder parameter, can be reinterpreted as special cases within this framework. As a concrete realization, we employ a distribution-free two-sample run test and demonstrate that the critical point of the two-dimensional Ising model is accurately identified without prior knowledge of the order parameter.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Lectures on Quantum Measurement Theory: IV

June 30 (Tue) 15:30 - 17:00, 2026

Masanao Ozawa (Professor Emeritus, Nagoya University)

Lecture IV: Instruments in classical mechanics, quantum field theory, and cognitive science In algebraic quantum field theory, measurements describable by interactions between the field and the measuring apparatus are characterized by the class of completely positive instruments that satisfy the condition called the normal extension property (NEP) (Okamura-Ozawa 2016). In classical mechanics, traditionally only non-invasive measurements—those with trivial interaction—were considered admissible, for the observability of the trajectory of motion. Here, however, the full class of measurements realizable by classical-mechanical interactions is characterized in terms of instruments with NEP for the basis of the study of invasive measurements of classical systems. Cognitive processes are also represented by completely positive instruments, along with the long-standing paradigm provided by von Helmholtz, who described a sensation-perception process as a sort of measuring interaction and referred to it as an unconscious inference. This framework is used to show the compatibility of the question order effect and the response replicability effect (Ozawa-Khrennikov 2019), which failed to be explained in an earlier approach using only projective measurement models. It is shown that there exists an instrument model, realizing both the question order effect and the response replicability effect, that is also capable of almost faithfully reproducing public-opinion survey data such as the well-known Clinton-Gore survey by Gallup in 1997 (Ozawa-Khrennikov 2021).

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Cosmic-ray bath in a past supernova gives birth to Earth-like planets

July 3 (Fri) 14:00 - 15:15, 2026

Ryo Sawada (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

A key question in astronomy is how ubiquitous Earth-like rocky planets are. The formation of terrestrial planets in our Solar System was strongly influenced by the radioactive decay heat of short-lived radionuclides (SLRs), particularly 26 Al (aluminum-26), likely delivered from nearby supernovae. However, current models struggle to reproduce the abundance of SLRs inferred from meteorite analysis without destroying the protosolar disk. We propose the "immersion" mechanism, where cosmic-ray nucleosynthesis in a supernova shockwave reproduces estimated SLR abundances at a supernova distance (~1 parsec), preserving the disk. We estimate that solar mass stars in star clusters typically experience at least one such supernova within 1 parsec, supporting the feasibility of this scenario. This suggests that Solar System─like SLR abundances and terrestrial planet formation are more common than previously thought.

Venue: #424-426, Main Research Building

Event Official Language: English

Thom polynomials relative to prescribed maps around the boundary

July 3 (Fri) 15:00 - 17:30, 2026

Masato Tanabe (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Thom polynomials are universal cohomological obstructions to the appearance of singularities of given types in differentiable maps. Introduced by R. Thom in the 1950s, they have been extensively studied ever since. In the first half of this talk, I would like to recall their theory with introduction of algebro-topological materials. In the second half, I would also like to talk about applications of Thom polynomials to topology of non-singular maps. Since this century, various invariants of immersions/embeddings have been expressed in terms of singularities of their extensions (a.k.a. singular Seifert surfaces). However, those formulas are obtained in different forms and remain somewhat scattered. As the first step to unify them, I would like to introduce Thom polynomials relative to prescribed maps around the boundary. As a main result, we show a structure theorem of Thom polynomials relative to framable immersions. In fact, most earlier formulas are summarized as the vanishing of "correction terms" appearing in the structure theorem. This is an advanced seminar for mathematical researchers.

Venue: Seminar Room #359, Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Toward an understanding of microbial circulation in the Mongolian nomadic ecosystem

July 6 (Mon) 13:00 - 14:00, 2026

Akari Shinoda (Assistant Professor, Faculty of Environmental, Life, Natural Science and Technology, Okayama University)

I have been studying microorganisms in the Mongolian nomadic ecosystem from several perspectives. First, I seek to characterize the microbial communities in traditional fermented dairy products—most notably airag (fermented mare's milk)—and their features. Second, I am analyzing the relationship between the traditional Mongolian diet and the gut microbiome. Third, focusing on environmental microorganisms (bioaerosols) in regions undergoing desertification, I aim to trace their origins and atmospheric transport. In the course of these studies, I have come to suspect that microorganisms may circulate among humans, livestock, fermented foods, and the environment. In this research, I aim to understand such microbial circulation by combining approaches from each of these perspectives and by investigating the relationships among these elements. In this talk, I will provide an overview of each topic and discuss the potential of an interdisciplinary approach that connects them.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Overview of quantum error correcting codes

July 7 (Tue) 15:00 - 16:30, 2026

Takaya Matsuura (Postdoctoral Researcher, Quantum Computing Theory Research Team, RIKEN Center for Quantum Computing (RQC))

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

How did we come to be? — Particle Physics for the Next Decades —

July 10 (Fri) 15:30 - 17:00, 2026

Hitoshi Murayama (Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo / Professor, Department of Physics, University of California, Berkeley, USA)

Particle Physics is a study of the smallest and the biggest to uncover the fundamental laws that govern the universe. In recent years, both the United States and Europe have been through long-range planning processes. The future plans worldwide include the studies of (1) neutrinos that may have saved us from a complete annihilation, (2) the Higgs boson that keeps us in one piece, (3) dark matter that assembled us from the primordial soup, (4) inflation that created the macroscopic universe, and (5) the exploration of unknown particles and forces. It requires development of mind-boggling technologies.

Venue: Okochi Hall (Main Venue) / via Zoom

Event Official Language: English

The 33th MACS Colloquium

July 17 (Fri) 14:45 - 18:00, 2026

Hajime Naruse (Professor, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)
Yohsuke Murase (Team Director, Mathematical Social Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

14:45-15:00 Teatime Discussion 15:00-16:00 Hajime Naruse (Professor, Department of Geophysics, Graduate School of Science, Kyoto University) "What Do Sedimentary Layers Remember? Exploring Past Earth Environments through Machine Learning" 16:15-17:15 Yosuke Murase (Team Director, Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN) "Mathematics of Cooperation in Society: The Evolution of Cooperation through Direct and Indirect Reciprocity" 17:15-18:00 Discussion

Venue: Science Seminar House (Map 9), Kyoto University

Event Official Language: Japanese

Workshop on Discrete & Continuous Aspects of Reaction-Diffusion in Pattern Formation

July 22 (Wed) - 24 (Fri) 2026

Ryoko Oishi-Tomiyasu (Professor, Institute of Mathematics for Industry, Kyushu University)
Makoto Sato (Professor, Kanazawa University)
Nobuhiko Suematsu (Professor, School of Interdisciplinary Mathematical Sciences, Meiji University)
Yasumasa Nishiura (Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)
Riccardo Muolo (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Jonathan Dawes (Professor, University of Bath, UK)
Henrik Weyer (Postdoctoral Scholar, University of California, Santa Barbara, USA)
Yuzuru Kato (Associate Professor, Department of Complex and Intelligent Systems, School of Systems Information Science, Future University-Hakodate)
Ayumi Ozawa (Young Research Fellow, Japan Agency for Marine-Earth Science and Technology (JAMSTEC))
Takanori Sugimoto (Associate Professor, Faculty of Engineering Science, Kansai University)
Natsuhiko Yoshinaga (Professor, School of Systems Information Science, Future University-Hakodate)
Jens Rademacher (Professor, University of Hamburg, Germany)
Takeshi Fukao (Professor, Faculty of Advanced Science and Technology, Ryukoku University)
Yoshitaro Tanaka (Associate Professor, School of Systems Information Science, Future University-Hakodate)
Shuji Ishihara (Project Associate Professor, The University of Tokyo)
Hiroshi Ishii (Assistant Professor, Research Institute for Electronic Science, Hokkaido University)
Takeshi Watanabe (Associate Professor, Nagano University)
Antoine Diez (Research Scientist, Mathematical Application Research Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Venue: via Zoom / Research Seminar Room 3, 6F, High-Rise Building, Meiji University (Nakano Campus)

Event Official Language: English

Hidden Networks: From Phase Reductions to Effective Network Interactions

August 24 (Mon) 15:30 - 17:00, 2026

Christian Bick (Associate Professor, Department of Mathematics, Vrije Universiteit Amsterdam, Netherlands)

From networks of interconnected neurons in the brain to coupled electrochemical reactions: The collective dynamics of interacting dynamical systems shape the function (or dysfunction) of many systems that are critical for our everyday lives. For coupled oscillatory processes, synchronization is a prime example of emergent collective dynamics. But how oscillators interact is not necessarily obvious from (physical) connections between the oscillators. Here we look at phase reductions as a way to uncover the hidden 'effective' network interactions for coupled oscillators dynamics. On the one hand, these give insight into when oscillators do and do not interact (despite a link). On the other hand, they elucidate when and how nonpairwise higher-order interactions shape synchronization phenomena in coupled oscillator networks.

Venue: Okochi Hall (Main Venue) / via Zoom

Event Official Language: English

iTHEMS-UTokyo Intensive Lectures on Quantum Gravity

August 31 (Mon) - September 2 (Wed) 2026

Hikaru Kawai (Visiting Professor, Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), Osaka Metropolitan University)

iTHEMS-UTokyo Intensive Lectures on Quantum Gravity (10th Quantum Gravity Gatherings Lecture Series) The 10th QGG Lecture Series is a special three-day installment of the intensive lecture series organized by the Quantum Gravity Gatherings (QGG) study group at RIKEN iTHEMS. This celebratory edition will feature Professor Hikaru Kawai from Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), who will deliver a series of lectures on themes related to quantum gravity. This lecture series will follow a style similar to Prof. Kawai's first QGG lectures, held three years ago at RIKEN (Wako) as the inaugural QGG event, which explored fundamental questions in quantum gravity, string theory, and the quantum universe. A distinctive feature of this 10th installment is that it will take place on the Komaba campus of The University of Tokyo, where one of the iTHEMS satellite offices is located. This will be the first QGG lecture series held outside Wako, with the aim of making the event more accessible to a broader group of participants. Format: Lectures will be given mainly in blackboard style and in English, encouraging active participation and in-depth Q&A discussions. Poster sessions will also be held, giving participants an opportunity to present their own work or topics of interest. These sessions are intended to foster communication and stimulate the exchange of ideas among participants. This event will take place in person only. Target audience: Senior scholars, early-career researchers, and students are all warmly welcome. Registration deadline: July 31, 2026

Venue: 21 Komaba Center for Educational Excellence (21 KOMCEE) East Building, Room K214, Komaba Campus, The University of Tokyo

Event Official Language: English

Efficient iBF: Balanced Integration of Fragmented Matching Markets for Welfare Improvement

September 4 (Fri) 15:30 - 17:00, 2026

Fuhito Kojima (Professor, Department of Economics, The University of Tokyo)

Matching markets often suffer from fragmentation, which leads to inefficiency. We model a fragmented market in a school-choice context and offer a practically relevant method for integration. Specifically, each student and school belong to a region, and we allow for inter-regional transfer of students with "balancedness" constraint: a matching is said to be balanced if, for each region, the outflow of students from that region to other regions is equal to the inflow of students from the latter to the former. Using a directed bipartite graph defined on students and schools, we characterize the set of Pareto efficient matchings among those that are individually rational, balanced and fair (efficient iBF). We also provide a class of polynomial-time algorithms to compute such matchings. When each region favors local students in their priority, the outcome of an algorithm from this class weakly improves student welfare upon the outcome where each region independently uses the deferred acceptance mechanism. Various real-life examples of fragmentation are discussed, and we illustrate how our method would address the issue.

Venue: Okochi Hall (Main Venue) / via Zoom

Event Official Language: English

The 11th Intensive Lectures on Quantum Gravity

September 7 (Mon) - 9 (Wed) 2026

Yasuyuki Hatsuda (Associate Professor, Department of Physics, Faculty of Science, Rikkyo University)

In the 11th event of the Intensive Lecture Series, organized by the Quantum Gravity Gatherings (QGG) study group at RIKEN iTHEMS, we will have Prof. Yasuyuki Hatsuda from Rikkyo University, who will deliver a three-day lecture series on the analytic methods in black hole perturbation theory. Black hole perturbation theory plays a very important role in the developments of modern physics. For instance, in gravitational wave astronomy, it can describe the ringdown phase during the merger events of binary black holes. As the frequency and decay rate of each quasinormal mode are unique to the remnant black hole, one can test extreme-gravity physics by extracting those modes from the ringdown signal. In addition, the computation of black hole quasinormal modes based on black hole perturbation theory has relations connecting to conformal field theories and even to the computations of tidal Love numbers. With the broad applications, we expect this lecture series to provide fresh perspectives to researchers across a wide range of fields and to inspire new directions in their own research. The lectures will be delivered in a blackboard-style format (in English), designed to foster interaction, active participation, and in-depth Q&A discussions. In addition, short talk sessions will be held, giving participants the opportunity to present briefly on topics of their choice. Through this informal and dynamic setting, we hope to spark active interactions among participants and create an environment where ideas can be shared openly and enthusiastically. This event will take place in person only. Target audience: Senior scholars, early-career researchers, and students are all warmly welcome. Registration deadline: July 31, 2026

Venue: #435-437, 4F, Main Research Building

Event Official Language: English

Majorana Modes: Fundamentals, Status & Directions

October 13 (Tue) - 16 (Fri) 2026

Workshop Overview Majorana modes lie at the heart of contemporary condensed-matter physics, exhibiting non-Abelian exchange statistics; when protected by topology, they are robust against environmental perturbations. Here, “Majorana mode” is used broadly to include a localized zero-energy Majorana state (a Majorana zero mode) and chiral Majorana edge states with gapless dispersion crossing zero energy. This three-day in-person workshop returns to fundamentals and open questions. It opens with a tutorial session on the afternoon of October 13 for non-experts and adjacent fields, and emphasizes rigorous theory–experiment dialogue, robust methodology, and concrete benchmarks for realizing and testing Majorana modes. Participants Experimentalists and theorists working on Majorana modes Researchers in adjacent fields (quantum materials, superconductivity, mesoscopic physics) Graduate students and postdocs interested in entering the field Topics include (non-exhaustive) Majorana zero modes in a variety of nanostructures Chiral Majorana edge states in quantum spin liquids and other platforms Disorder, interactions, and realistic device modeling Experimental diagnostics and “smoking gun” signatures Topological Quantum Spin Systems

Venue: Okochi Hall

Event Official Language: English

AI and Scientific Discovery

October 19 (Mon) 14:00 - 15:30, 2026

Joseph Ledsam (Google Health Lead, Japan, Google Japan)

Artificial intelligence is having a transformative impact on health and scientific discovery. This presentation will trace the evolution from foundational breakthroughs to the sophisticated capabilities of today's large-scale AI models. It will explore how these advanced systems are creating new possibilities across the healthcare landscape, from accelerating therapeutic development to enhancing diagnostic processes and interpreting complex medical data. The session will also take a deeper look at the future possibilities for AI in health and explore the emerging role of agentic AI in scientific discovery. The core theme is the responsible development of AI to create tools that assist scientists, support healthcare professionals, and empower users. Bio: Dr Joseph Ledsam leads Google Health in Japan, where he works across AI research, digital health and health in Google products. He has led research in medical AI, genomics and drug discovery published in journals including Nature, Nature Medicine and Nature Methods. Before moving to Japan he worked as a medical doctor in the UK, and founded the Health Research and Genomics teams in Google DeepMind. He obtained his medical degree from The University of Leeds, UK, and was a research fellow at University College London during his clinical residency.

Venue: #435-437, Main Research Building (Main Venue) / via Zoom

Event Official Language: English