Seminar
996 events
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SeminarAI and Scientific Discovery
June 3 (Wed) 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
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Seminar
Bootstrapping Cosmological Correlators
May 28 (Thu) 16:00 - 18:00, 2026
Mang Hei Gordon Lee (Post-Doctoral fellow, Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taiwan)
Currently there are hundreds of models describing inflation, a period of accelerated expansion in our universe. Each model lead to different imprints in cosmological observables, and for the purpose of testing the idea of inflation itself, it is essential to understand which predictions are model independent. This lead to the idea of cosmological bootstrap, a set of constraints from physical principles and symmetries alone. In this talk I will give an overview on the cosmological bootstrap program. I will first explain how locality, unitarity and symmetry can constrain the kinematics of cosmological correlators. I will then talk about some recent progress on constructing positivity bounds on cosmology, which places constraints on the interactions of fields in inflation.
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building
Event Official Language: English
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Seminar
Singularities of differentiable maps and Thom polynomials
May 22 (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))
Singularities are locations where something is exceptional. In particular, singularities of differentiable maps are mathematical concepts corresponding to stationary points of functions and apparent contours of surfaces under projection onto the retina. These are unavoidable in general, but important to study the shape of spaces and behavior of maps. The theory for them was initiated by R. Thom in 1950's, and have been deeply studied by many researchers.
Venue: Room 359, RIKEN Wako Campus (Main Venue) / via Zoom
Event Official Language: English
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SeminarIntroduction to quantum resource theories (3)
May 15 (Fri) 9:00 - 17:00, 2026
Ryuji Takagi (Associate Professor, Graduate School of Arts and Sciences, The University of Tokyo)
[Registration Closed] Due to high demand and venue capacity limits, registration for this course is now closed as of April 25. If you wish to be placed on a waiting list in case of cancellations, please contact us via the inquiry form at the bottom of this page. One of the central goals of quantum information theory is to quantitatively clarify the relationship between the performance of quantum information processing and the valuable quantum features that underlie it. In this lecture, we will discuss quantum resource theories, a framework that provides a useful approach to this question. By presenting concrete examples—starting with entanglement theory, the most representative resource theory—as well as recent research results, we will see how perspectives and tools from information theory enable the quantification of quantum resources and the characterization of their convertibility. Beyond entanglement theory, we plan to discuss other key settings such as quantum thermodynamics, resource theory of asymmetry, and quantum magic—relevant resource in fault-tolerant quantum compuation. The overall aim of this lecture is to provide new analytical viewpoints that can be applied to a wide range of systems and quantum information processing tasks. While we do not plan to change the overall start and end times for each day, the detailed lecture schedule is subject to change. The intensive course will be held over three days. Please register for the course using the form. The registration deadline is May 7 (Thu). Please note that the registration form is the same for all three days, so you only need to register once. The 3rd day: May 15 (Fri) 9:00–10:30 Lecture 7 10:30–11:00 Coffee break 11:00–12:30 Lecture 8 12:30-13:30 Lunch time 13:30-15:00 Free discussion/Summary of the lectures 15:00-15:30 Coffee break 15:30-17:00 Lecture 9/Seminar This event is in-person only.
Venue: #435-437, 4F, Main Research Building
Event Official Language: English
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SeminarStochastic Schrödinger Diffusion Models for Pure-State Ensemble Generation
May 14 (Thu) 14:30 - 15:30, 2026
Jian Xu (Postdoctoral Researcher, Quantum Mathematical Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
In quantum machine learning (QML), classical data are often encoded as quantum pure states and processed directly as quantum representations, motivating \emph{representation-level generative modeling} that samples new quantum states from an underlying pure-state ensemble rather than re-preparing them from perturbed classical inputs. However, extending \emph{score-based} diffusion models with well-defined reverse-time samplers to quantum pure-state ensembles remains challenging, due to the non-Euclidean geometry of the complex projective space $\mathbb{CP}^{d-1}$ and the intractability of transition densities. We propose \emph{Stochastic Schr\"odinger Diffusion Models} (SSDMs), an intrinsic score-based generative framework on $\mathbb{CP}^{d-1}$ endowed with the Fubini--Study (FS) metric. SSDMs formulate a forward Riemannian diffusion with a stochastic Schr\"odinger equation (SSE) realization, and derive reverse-time dynamics driven by the Riemannian score $\nabla_{\mathrm{FS}} \log p_t$. To enable training without analytic transition densities, we introduce a local-time objective based on a local Euclidean Ornstein--Uhlenbeck approximation in FS normal coordinates, yielding an analytic teacher score mapped back to the manifold. Experiments show that SSDMs faithfully capture target pure-state ensemble statistics, including observable moments, overlap-kernel MMD, and entanglement measures, and that SSDM-generated quantum representations improve downstream QML generalization via representation-level data augmentation.
Venue: #359, Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
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Seminar
From Birkhoff's Polytope to Petz Recovery: Unistochastic Matrices, Quantum Channels, and Approximate Markov Chains
May 13 (Wed) 13:30 - 15:00, 2026
Claude Gravel (Assistant Professor, Department of Computer Science, Toronto Metropolitan University, Canada)
A doubly stochastic matrix is unistochastic if its entries correspond to the squared moduli of a unitary matrix. Determining which n × n doubly stochastic matrices admit such a representation remains an open problem at the intersection of convex geometry, combinatorics, and quantum information. For 3 × 3 matrices, elegant triangle inequalities provide a complete characterization: the unistochastic set occupies approximately 75% of the Birkhoff polytope and exhibits deltoid cross-sections. For n ≥ 4, the characterization problem remains unresolved and is influenced in unexpected ways by the prime factorization of n via the defect of the Fourier matrix. This presentation surveys these results and then establishes a connection to a second, seemingly unrelated question: given a tripartite quantum state with small conditional mutual information, to what extent can one subsystem be recovered from the others? The Petz recovery map and its rotated variants offer a universal solution. These two topics are linked through coherification, which concerns when a classical stochastic process can be elevated to coherent quantum dynamics, and through the conditional mutual information as a continuous measure of non-unistochasticity. The talk concludes with open problems at this interface, including the star-shapedness conjecture for n = 4 and the pursuit of tighter recovery bounds.
Venue: #359, Seminar Room #359
Event Official Language: English
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Seminar
Introduction to quantum resource theories (2)
May 12 (Tue) 9:00 - 17:00, 2026
Ryuji Takagi (Associate Professor, Graduate School of Arts and Sciences, The University of Tokyo)
[Registration Closed] Due to high demand and venue capacity limits, registration for this course is now closed as of April 25. If you wish to be placed on a waiting list in case of cancellations, please contact us via the inquiry form at the bottom of this page. One of the central goals of quantum information theory is to quantitatively clarify the relationship between the performance of quantum information processing and the valuable quantum features that underlie it. In this lecture, we will discuss quantum resource theories, a framework that provides a useful approach to this question. By presenting concrete examples—starting with entanglement theory, the most representative resource theory—as well as recent research results, we will see how perspectives and tools from information theory enable the quantification of quantum resources and the characterization of their convertibility. Beyond entanglement theory, we plan to discuss other key settings such as quantum thermodynamics, resource theory of asymmetry, and quantum magic—relevant resource in fault-tolerant quantum compuation. The overall aim of this lecture is to provide new analytical viewpoints that can be applied to a wide range of systems and quantum information processing tasks. While we do not plan to change the overall start and end times for each day, the detailed lecture schedule is subject to change. The intensive course will be held over three days. Please register for the course using the form. The registration deadline is May 7 (Thu). Please note that the registration form is the same for all three days, so you only need to register once. The 2nd day: May 12 (Tue) 9:00–10:30 Lecture 3 10:30–11:00 Coffee break 11:00–12:30 Lecture 4 12:30-13:30 Lunch time 13:30-15:00 Lecture 5 15:00-15:30 Coffee break 15:30-17:00 Lecture 6 This event is in-person only.
Venue: #435-437, 4F, Main Research Building
Event Official Language: English
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Seminar
Introduction to quantum resource theories (1)
May 11 (Mon) 13:30 - 17:00, 2026
Ryuji Takagi (Associate Professor, Graduate School of Arts and Sciences, The University of Tokyo)
[Registration Closed] Due to high demand and venue capacity limits, registration for this course is now closed as of April 25. If you wish to be placed on a waiting list in case of cancellations, please contact us via the inquiry form at the bottom of this page. One of the central goals of quantum information theory is to quantitatively clarify the relationship between the performance of quantum information processing and the valuable quantum features that underlie it. In this lecture, we will discuss quantum resource theories, a framework that provides a useful approach to this question. By presenting concrete examples—starting with entanglement theory, the most representative resource theory—as well as recent research results, we will see how perspectives and tools from information theory enable the quantification of quantum resources and the characterization of their convertibility. Beyond entanglement theory, we plan to discuss other key settings such as quantum thermodynamics, resource theory of asymmetry, and quantum magic—relevant resource in fault-tolerant quantum compuation. The overall aim of this lecture is to provide new analytical viewpoints that can be applied to a wide range of systems and quantum information processing tasks. While we do not plan to change the overall start and end times for each day, the detailed lecture schedule is subject to change. The intensive course will be held over three days. Please register for the course using the form. The registration deadline is May 7 (Thu). Please note that the registration form is the same for all three days, so you only need to register once. The 1st day: May 11 (Mon) 13:30-15:00 Lecture 1 15:00-15:30 Coffee break 15:30-17:00 Lecture 2 This event is in-person only.
Venue: #435-437, 4F, Main Research Building
Event Official Language: English
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SeminarSix operations in differential topology
May 8 (Fri) 15:00 - 17:00, 2026
Takumi Maegawa (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
The formalism of six operations, pioneered by Grothendieck and Verdier, serves as a unifying framework for studying cohomological phenomena. This language realizes Poincaré-type duality and transfer maps as certain adjunctions between stable $\infty$-categories of sheaves. In this talk, we highlight the theory of six operations in topology and apply it to provide an intrinsic version of the Pontryagin-Thom construction. We then discuss the intrinsic construction of invariants coming from Seiberg-Witten theory, which is based on the speaker's previous work.
Venue: via Zoom
Event Official Language: English
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Seminar Tomorrow
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
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Seminar
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
996 events