Building autonomous AI physicists for frontier physics research

April 30 (Thu) 15:00 - 16:00, 2026

Tingjia Miao (Ph.D. Student, School of Artificial Intelligence, Shanghai Jiao Tong University, China)

Advances in LLMs have led to agents with knowledge and operational capabilities comparable to human scientists, suggesting potential to assist, accelerate, and automate research. Physics, especially theoretical and computational physics, which requires integrating analytical reasoning, code-based computation, and profound domain expertise, is well suited for verifying the end-to-end research capabilities of AI scientists. Accordingly, we construct a general-purpose AI physicist PhysMaster, equipped with a layered academic knowledge base, adapted to the agent skill ecosystem, and adopting an adaptive exploration strategy that balances efficiency and exploration, enabling robust performance in ultra-long-horizon tasks; PhysMaster has been open-sourced. Meanwhile, we introduce PRL-Bench (Physics Research by LLMs), a benchmark with 100 tasks adapted from recent Physical Review Letters papers, covering astrophysics, condensed matter physics, high-energy physics, quantum information, and statistical physics. Evaluation across frontier models shows that failures are dominated by conceptual and formulaic errors, and that exploration and derivations remain unstable over long horizons. In addition, we develop domain-specialized AI scientists, including LQCD Master, which integrates Lattice QCD workflows and expert skills, enabling automated generation and submission of lattice computation scripts from concise physics goals.

Venue: via Zoom

Event Official Language: English

Uniform Matrix Product States for Hamiltonian Lattice Gauge Theories: Methods and Applications

April 28 (Tue) 16:00 - 17:30, 2026

Kohei Fujikura (Research Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University)

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

Event Official Language: English

DEEP-IN WG Sarter Meeting 2026

April 27 (Mon) 15:30 - 17:00, 2026

Tae-Geun Kim (Postdoc, Fudan University, China)
Yang-Yang Tan (Postdoctoral Fellow, The University of Tokyo)
Masato Taki (Associate Professor, Graduate School of Artificial Intelligence and Science, Rikkyo University)

15:30–16:00 NOW&NEXT of DEEP-IN WG (Lingxiao Wang) Self-Introduction of Members 16:00–16:20 AI Team and DEEP-IN (Masato Taki) 16:20–16:40 Inverse Problems in HEP (Tae-Geun Kim, FudanU) 16:40–17:00 Inverse Modeling Distributions (Yang-yang Tan, UTokyo)

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

Event Official Language: English

Cooking up holographic black holes

April 27 (Mon) 13:30 - 15:00, 2026

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

I have recently been investigating holography for open systems and have developed a method to compute correlation functions of a CFT governed by the Lindblad equation from its gravitational dual. In an open system, the state of the subsystem of interest cannot remain pure, and one naively expects its entropy to grow over time. It is then natural to expect that this thermalization process is accompanied, on the gravity side, by black hole formation. In this talk, after giving an overview of holography for open systems, I will present a numerical nonperturbative analysis of the dynamics of JT gravity coupled to a scalar field, and show that black holes indeed form in this setup.

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

Event Official Language: English

Mathematical Application Research Team Meeting #14

April 24 (Fri) 14:00 - 15:30, 2026

Shin-ichi Ohta (Professor, School of Science, Osaka University)

Mathematical Application Research Team is honored to invite Prof. Shin-ichi Ohta from the University of Osaka to this meeting. Everyone is welcome to join the meeting to listen to his seminar. Title: Synthetic and comparison Lorentzian geometry Abstract: In this talk we review recent developments of synthetic geometric approaches to Lorentzian geometry, motivated by the theory of less regular spacetimes in general relativity as well as comparison geometry in the Riemannian setting. Among others, optimal transport theory plays a vital role.

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

Event Official Language: English

Cautionary tales in data analysis from gravitational-wave astronomy

April 23 (Thu) 13:00 - 14:00, 2026

Kipp Cannon (Professor, Research Center for the Early Universe (RESCEU), The University of Tokyo)

We'll look at signal detection in noisy data, and at Bayesian inference in astrophysical inverse problems. We'll look at the form these problems take in the context of gravitational-wave astronomy, but we'll focus on where attempts at solutions have gone wrong. The mistakes we make transcend disciplines, and hopefully by shining light on them others can be helped to avoid making them as well.

Venue: Hybrid Format (3F #359 and Zoom), Main Research Building

Event Official Language: English

The math that shows a perfect democracy is impossible

April 23 (Thu) 10:30 - 11:30, 2026

Brian Andrew Mintz (Postdoctoral Researcher, Mathematical Social Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Groups need to make decisions, and there are a wide variety of ways this can be done, each maximizing different notions of fairness. Social Choice Theory provides a mathematical framework to investigate these possibilities rigorously. Infamous for its many impossibility results, this topic reveals some fundamental limits to democracy. Beyond this, we'll discuss potential resolutions to these problems, as well as their real world implications.

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

Event Official Language: English

Seeing Photons, from Einstein to Bohr to Hanbury Brown-Twiss and related Hong-Ou-Mandel Interference Phenomena

April 22 (Wed) 15:00 - 16:30, 2026

Gordon Baym (Professor Emeritus, University of Illinois, USA)

Why do we believe that the electromagnetic field is quantized, and photons exist? This talk will focus on two ways that the quantization of the electromagnetic field manifests itself in interference experiments. Bohr, who initially doubted photons after Einstein's initial proposal of the photon to explain the photoeffect, eventually proposed a thought experiment showing that the consistency of elementary quantum mechanics at the level of two slit diffraction requires the quantization of the electromagnetic field. In addition, as I will argue, both Hanbury Brown-Twiss interferometry and the closely related Hong-Ou-Mandel effect provide yet another way to see that the electromagnetic field must be quantized.

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

Event Official Language: English

(Physics) Journal Club

April 22 (Wed) 14:00 - 15:00, 2026

Please check the papers and post anything interesting in the #phys_journal_club Slack channel!

Venue: 4th floor public space, Main Research Building

Event Official Language: English

Quantum Computing of Molecular Properties for Fundamental Physics

April 21 (Tue) 16:30 - 18:00, 2026

Pradyot Pritam Sahoo (Graduate International Research Student, Graduate School of Science, The University of Tokyo)

This is the self-introduction talk by Pradyot Pritam Sahoo. Pradyot is a Student Trainee in iTHEMS.

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

Event Official Language: English

Quantum generative learning via diffusion

April 21 (Tue) 10:00 - 11:00, 2026

Zhang Bingzhi (PostDoc, University of Southern California, USA)

Deep generative models are key-enabling technology to computer vision, text generation, and large language models. Generative models for quantum data offer a promising route toward learning and preparing complex quantum-state ensembles. In this talk, I will introduce the quantum denoising diffusion probabilistic model (QuDDPM) [1], which adapts the diffusion-model idea to quantum systems through a forward randomization process and a trainable backward denoising dynamics. I will discuss how this framework enables stepwise learning of target quantum state ensembles and demonstrate its capabilities in various learning tasks. I will then present its extension to mixed states to eliminate the need for scrambling [2]. I will conclude with a brief discussion of recent results on scaling laws of quantum information lifetime in monitored quantum dynamics, emphasizing how mid-circuit measurements can maintain information and provide useful intuition for measurement-assisted quantum machine learning.

Venue: via Zoom

Event Official Language: English

Challenges in virology & neurodegeneration: improving experimental procedures and theoretical insights

April 20 (Mon) 14:00 - 15:00, 2026

Catherine Beauchemin (Deputy Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

After repeatedly finding errors in experimental data provided by collaborators, my group developed an online tool (midSIN, https://midsin.roadcake.org/) to improve estimating the concentration of infectious viruses in samples. This led to an unexpected new collaboration with researchers working to measure the concentration of aggregating fibrils in samples from patients suffering from neurodegenerative diseases such as Dementia with Lewy Body and Parkinson's. In the first part of my talk, I will introduce the basics of how infectious virions and aggregating fibril concentrations are measured experimentally, and discuss challenges in tackling these assays' limitations to improve their accuracy and sensitivity. In the second part of my talk, I will discuss the challenges we face in trying to identify the type and minimal number of experimental measurements required to predict the severity and transmission efficacy of diverse influenza viruses collected as part of pandemic surveillance efforts. I hope you will join the talk to learn of these challenges and consider contributing new ideas or approaches to overcome them.

Venue: Hybrid Format (4F #435-437 and Zoom), Main Research Building

Event Official Language: English

Analytical parametrization of the primordial power spectrum in effective Loop Quantum Cosmology

April 20 (Mon) 13:00 - 14:00, 2026

Almudena Sánchez Guillén (Ph.D. Student, Institute of Structure of Matter (IEM-CSIC), Spain)

We investigate the imprints on the angular power spectra of cosmological perturbations of a pre-inflationary bounce phase, as described by the hybrid and dressed metric approaches to loop quantum cosmology. For this purpose, we derive a new parametrization of the primordial power spectrum at the end of the inflationary regime. Apart from slow-roll coefficients and cosmological parameters that are present in the standard cosmological scenario without quantum modifications, this parametrization additionally depends only on pre-inflationary physics. More specifically, we find a dependence on the number of e-folds during the bounce epoch and on a characteristic suppression scale which, given the e-folds accumulated during cosmic evolution, is determined by the energy density at the bounce.

Venue: via Zoom / Seminar Room #359

Event Official Language: English

iTHEMS x academist Online Event "World of Mathematical Sciences 2026"

April 18 (Sat) 10:00 - 15:30, 2026

Junnosuke Koizumi (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Osamu Fukushima (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Muzi Hong (Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Kenji Okubo (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Venue: via Zoom

Event Official Language: Japanese

TJR-iTHEMS Joint Seminar: Golden Age of Neutron Stars

April 17 (Fri) 16:00 - 17:00, 2026

Gordon Baym (Professor Emeritus, University of Illinois, USA)

This is a TJR-iTHEMS Joint Seminar supported by ASPIRE Program ABSTRACT Neutron stars were first posited in the early thirties, and discovered as pulsars in the late sixties; however we are only recently beginning to understand the matter they contain. I will describe the ongoing development of a consistent picture of the liquid interiors of neutron stars, now driven by ever increasing observations as well as theoretical advances. These include observations of heavy neutron stars of about 2.0 solar masses and higher; ongoing inferences of masses and radii by the NICER telescope; and observations of binary neutron star mergers, through gravitational waves as well as across the electromagnetic spectrum. Theoretically an understanding is emerging in QCD of how nuclear matter can turn into deconfined quark matter, which I will illustrate with modern quark-hadron crossover equations of state. BRIEF BIO Gordon Baym is a Professor of Physics at the University of Illinois. Educated at Cornell and Harvard, he spent two years at the Niels Bohr Institute. His interests range from matter under extreme conditions to ultracold atomic physics, astrophysics, and nuclear physics. A pioneer in the study of pulsars and neutron stars, he is a member of the U.S. National Academy of Sciences and received the APS Medal for Exceptional Achievement in Research, the Hans Bethe and Lars Onsager Prizes, and the Eugene Feenberg Memorial Medal.

Venue: H701, The University of Osaka, Toyonaka Campus

Event Official Language: English

RIKEN Seminar: Formulation of Life Phenomena from Quantum Theory

April 16 (Thu) 14:00 - 16:05, 2026

13:45 Opening 14:00-14:05 Introduction Atsushi Iriki (Teikyo University Advanced Comprehensive Research Organization Division of Artificial Intelligence, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS)) 14:05-14:35 "Interpretation of Life Phenomena Using Quantum Wave Functions and Field Theory" Kazuhiro Sakurada (Keio University Medical School and RIKEN Center for Integrative Medical Sciences (IMS), Predictive Medicine Special Project (PMSP)) 14:35-14:45 Q&A 14:45-15:30 "Bridging neurophysiology and quantum-like cognition" Andrei Khrennikov (Center for Mathematical Modeling in Physics and Cognitive Sciences Linnaeus University) 15:30-15:45 Q&A 15:45-16:00 "Quantum-Like Measurement" Masanao Ozawa (RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN TRIP FQSP, and Nagoya University) 16:00-16:05 Closing Remarks Satoshi Iso (Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS)) Host Laboratory: Predictive Medicine Special Project, RIKEN Center for Integrative Medical Sciences (IMS) / RIKEN Center for Interdisciplinary Theoretical and Mathematical Science (iTHEMS) *Registration is required by April 14 via the registration form. Contact: Predictive Medicine Special Project (pmsp-web@ml.riken.jp)

Venue: Meeting Room 305, Brain Science Ikenohata Research Bldg. (C56), RIKEN Wako Campus

Event Official Language: English

Searching For Anomalies with Foundation Models

April 16 (Thu) 14:00 - 15:30, 2026

Vinicius Massami Mikuni (Associate Professor, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University)

This is a joint seminar with Institute for Physics of Intelligence (iπ), UTokyo Anomaly detection relaxes the assumptions of how new physics should look and extends the reach of what we can discover. However, interpreting the data and estimating backgrounds remains a challenge. In this new work, we investigate anomalous events selected by the OmniLearned Foundation model across different model sizes, performing a full analysis using CMS Open Data. Surprisingly, models of different sizes, trained on the same data with the same loss functions, select entirely different collisions. In particular, the large OmniLearned model (500M parameters) selects events that are not well described by our background model.

Venue: Faculty of Science Bldg.1, School of Science, The University of Tokyo, Hongo Campus (Main Venue) / via Zoom

Event Official Language: English

Understanding Biological Clocks Using Methods from Applied Mathematics and Theoretical Physics

April 16 (Thu) 12:30 - 13:30, 2026

Gen Kurosawa (Senior Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Imagine that you are in a room with no information about time. The room is located in a cave, where temperature and light intensity remain constant. In such an environment, would you be able to wake up tomorrow or the day after? In fact, most humans can wake up at roughly similar times on successive days. This is because we possess internal daily rhythms, known as circadian rhythms. Biological experiments have shown that such rhythms are not unique to humans, but are shared by many species on Earth. In this talk, I will introduce some open problems related to these daily rhythms, and discuss approaches based on dynamical systems theory and the renormalization group method, from the perspectives of applied mathematics and theoretical physics.

Venue: via Zoom / Seminar Room #359

Event Official Language: English

iTHEMS NOW & NEXT 2026

April 13 (Mon) - 14 (Tue) 2026

We will hold an annual in-house gathering, “iTHEMS NOW & NEXT,” for FY 2026. The event provides a great opportunity for all iTHEMS members, including visiting researchers and, in particular, new arrivals, to gain a comprehensive overview of iTHEMS’s current activities and future directions. The detailed program will be announced in due course, but there will be poster sessions for all members, so please be ready to present one.

Venue: 2F Large Conference Room, Administrative Headquarters, RIKEN Wako Campus (Main Venue) / via Zoom

Event Official Language: English

From Classical Definiteness to Geometric Predictability: Complementarity, Coherence, and Thermodynamic Triality

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

Ezra Acalapati Madani (Ph.D. Student, Laboratoire de Physique de l'École Normale Supérieure, France)

Wave–particle complementarity is one of the central principles of quantum mechanics, traditionally quantified through the Englert–Greenberger–Yasin relation between which-way information and interference visibility. In higher-dimensional and resource-theoretic settings, however, visibility is no longer unique, and it becomes natural to reformulate complementarity in terms of basis-dependent predictability, coherence, and mixedness. In this talk, I present two related works along this line. First, I discuss an exact complementarity relation between classical definiteness and quantumness, where definiteness is defined operationally through the resilience of a quantum state under nonselective dichotomic yes/no measurements, while the complementary quantum contribution is quantified using a Kirkwood–Dirac-based notion of coherence/interference motivated by recent KD-based coherence measures. Second, I introduce a geometric predictability defined by the Bures distance between the dephased state and the maximally mixed state. This predictability depends only on the observed measurement statistics and admits a closed form in terms of the Bhattacharyya overlap. For pure states, it satisfies an exact complementarity relation with nonclassical Kirkwood–Dirac coherence; for mixed states, this motivates a convex-roof extension whose operational meaning is the classically irreducible part of measurement randomness, with implications for guessing probability and min-entropy. Finally, motivated by the decomposition of entropy production into population and coherence contributions in quantum thermodynamics, and by standard wave–particle–mixedness triality relations, I show how the usual predictability–coherence duality can be promoted into a triality relation involving predictability, coherence, and mixedness. Altogether, the talk connects wave–particle duality, coherence resource theories, operational guessing tasks, and thermodynamic balance relations within a unified framework.

Venue: #359, Seminar Room #359

Event Official Language: English