セミナー

Computer Algebra with Deep Learning

2025年9月5日(金) 15:00 - 17:00

石原 侑樹 (日本大学 理工学部 数学科 助教)

Computer algebra is a field that aims to perform various mathematical calculations on computers. In recent years, there has been a surge in efforts to accelerate computer algebra algorithms using deep learning models such as “Transformer,” which is used in ChatGPT. In this lecture, I will introduce the results of joint research with Professor Kera et al. on learning Gröbner bases with Transformer.

会場: via Zoom / セミナー室 (359号室) 3階 359号室

イベント公式言語: 英語

iTHEMS Biology welcomes another new member!

2025年8月7日(木) 13:00 - 14:15

ソンジ・コン (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

This meeting will be used to welcome another new members to the iTHEMS Biology Study Group: Dr. Sungsik Kong, who is joining iTHEMS Fundamental Division as a Research Scientist. He will give us a 15-20 min talk to introduce his research. If time permits, let's also use this time to catch up on each other's current research. I hope that many people will join us to welcome this new member and come meet him and hear about his research.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Targeting SARS-CoV-2 RNA: Insights for RNA-Directed Drug Discovery

2025年7月31日(木) 13:00 - 14:30

マリア・イヴォニナ (九州大学 エネルギー研究教育機構 学術研究員)

Traditional pharmacology fights virus infections by targeting proteins including enzymes, receptors, and structural proteins to break up the viral machinery. Nucleic acid-targeting therapies, on the other hand, can act directly on the genetic code of viruses, blocking their replication or translation in host cells. Coronaviruses and HIV are examples of RNA viruses that use a process called -1 programmed ribosomal frameshifting (-1 PRF) to produce their viral proteins. In this process, the translating ribosome is forced to shift into the alternative reading frame, replicating mRNA in the wrong order. Using small-molecule compounds to block this mechanism could be a promising way to neutralize such viruses. It is difficult to experimentally study the interactions between RNA and a drug candidate to understand where the drug binds and how it changes the shape of the viral RNA. I will discuss how Molecular Dynamics simulations are used to explore the conformational dynamics of mRNA structural elements and to investigate what happens when an antiviral agent binds to it. Additionally, I will show how the quantum-chemical orbital interaction analysis we developed, called Through-Space/Through-Bond Energy Decomposition Analysis (TS/TB-EDA), reveals which RNA nucleotides, at the atomic level, are critical for binding. This molecular modelling approach reveals strategies for targeting structured RNA elements — a crucial step toward expanding the arsenal of RNA-targeting therapeutics for future pandemics.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Bridging applied math and quantum many-body physics and beyond via tensor methods

2025年7月23日(水) 16:00 - 17:00

品岡 寛 (埼玉大学)

In modern physics, high-dimensional functions and operators naturally arise in a wide range of contexts, including turbulence simulations, parameter-dependent partial differential equations (PDEs), and quantum field theory. Efficient representations and computations with such high-dimensional objects pose major challenges across disciplines. Dimensionality reduction techniques such as the Quantics Tensor Train (QTT) [1] and Tensor Cross Interpolation (TCI) [2] were originally developed in applied mathematics. In our work, we have extended these methods to quantum many-body problems, demonstrating their effectiveness in handling complex high-dimensional structures in theoretical physics [3–10]. Given their generality, QTT and TCI are expected to find applications beyond quantum theory itself, in fields such as statistical field theory, model reduction, and control of complex systems, where similar high-dimensional structures emerge. This presentation will first review the computational bottlenecks that arise in quantum many-body simulations and other high-dimensional problems. Then, we will introduce QTT and TCI from a broader, method-oriented perspective, aiming to bridge applied mathematics and quantum theoretical physics.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Supersymmetric field theories and homotopy theory

2025年7月23日(水) 13:00 - 14:30

山下 真由子 (Junior Research Faculty member, Perimeter Institute for Theoretical Physics, Canada)

I will give a general introduction and overview on the Segal-Stolz-Teichner program, which tries to relate supersymmetric field theories in physics with homotopy theory in mathematics.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Mesoscopic transport via one-dimensional chain with Localized two-body loss

2025年7月23日(水) 10:00 - 11:30

柿元 健佑 (早稲田大学 理工学術院 基幹理工学部 博士課程)

Abstract: Mesoscopic transport has long served as a powerful probe into the quantum behavior of matter; however, the role of dissipation in such systems remains unresolved. In recent years, quantum simulations of mesoscopic systems with ultracold atomic gases have made significant progress, particularly through the use of optical tweezers to induce local dissipation via atom loss. In this talk, we discuss a two-terminal mesoscopic system in which two-body loss occurs locally at the center of a one-dimensional chain, modeling a dissipative quantum point contact. To analyze this setup, we employ the Keldysh Green’s function formalism in combination with a noise-field representation of Lindblad dynamics. Our analysis reveals that the dissipation strength depends on the occupation number of the central dissipative site, leading to a weaker suppression of particle current in the weakly dissipative regime compared to the case of one-body loss.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

A free probability approach to quantum chaos in random matrix ensembles

2025年7月22日(火) 16:00 - 17:00

プラティック・ナンディ (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 特別研究員)

In free probability theory, quantum chaos is marked by “free independence” between observables at early and late times, causing certain statistical measures (cumulants) to vanish. Motivated by this, we study the statistics of a time-evolved operator in the Rosenzweig-Porter (RP) random matrix ensembles. Analyzing operator statistics for different spin operators across these regimes reveals close alignment with free probability predictions in the ergodic phase, contrasted by persistent deviations in the fractal and localized phases even at late times. Using the distance measures and statistical methods, we define and characterize the onset of the free time in the ergodic phase. The talk is based on arXiv: 2506.04520.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Detectability of post-Newtonian classical and quantum gravity via quantum clock interferometry

2025年7月22日(火) 14:00 - 15:00

若桑 江友里 (名古屋大学 大学院情報学研究科数理情報学専攻 特任准教授)

Understanding physical phenomena at the intersection of quantum mechanics and general relativity remains a major challenge in modern physics. While various experimental approaches have been proposed to probe quantum systems in curved spacetime, most focus on the Newtonian regime, leaving post-Newtonian effects such as frame dragging largely unexplored. In this study, we propose and theoretically analyze an experimental scheme to investigate how post-Newtonian gravity affects quantum systems. We consider two setups: (i) a quantum clock interferometry configuration designed to detect the gravitational field of a rotating mass, and (ii) a scheme exploring whether such effects could mediate entanglement between quantum systems. Due to the symmetry of the configuration, the proposed setup is insensitive to Newtonian gravitational contributions but remains sensitive to the frame-dragging effect. Assuming the validity of the quantum equivalence principle, this approach may provide insights not only into the quantum nature of gravity but also into whether spacetime itself exhibits quantum properties. However, our analysis reveals that, within realistic experimental parameters, the expected effects are too small to be detected. We discuss possible interpretations of this undetectability, and its implications for tests of quantum gravity.

会場: 研究本館 (メイン会場) / via Zoom

イベント公式言語: 英語

ComSHeL collaboration planning

2025年7月22日(火) 14:00 - 15:00

The objective of this 3rd monthly meeting of the ComSHeL Study Group is to discuss specific collaborations we could undertake across our own Teams/Divisions on projects of common interest to take advantage of our complementary skills and expertise. We also want to consider how ComSHeL could help respond to specific calls for focus in certain research areas within RIKEN and the broader funding landscape.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Peaks sphericity of non-Gaussian random fields

2025年7月22日(火) 10:30 - 12:00

上保 みちる (お茶の水女子大学 理学部 博士課程／日本学術振興会 特別研究員 DC)

We formulate the statistics of peaks of non-Gaussian random fields and implement it to study the sphericity of peaks. For non-Gaussianity of the local type, we present a general formalism valid regardless of how large the deviation from Gaussian statistics is. For general types of non-Gaussianity, we provide a framework that applies to any system with a given power spectrum and the corresponding bispectrum in the regime in which contributions from higher-order correlators can be neglected. We present an explicit expression for the most probable values of the sphericity parameters, including the effect of non-Gaussianity on the profile. We show that the effects of small perturbative non-Gaussianity on the sphericity parameters are negligible, as they are even smaller than the subleading Gaussian corrections. In contrast, we find that large non-Gaussianity can significantly distort the peak configurations, making them much less spherical.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Thermal evolution of accreting neutron stars

2025年7月20日(日) 16:00 - 17:30

Martin Javier Nava-Callejas (Postdoc, Université Libre de Bruxelles, Belgium)

Neutron stars undergoing mass accretion at low-mass X-ray binary systems (LMXBs) represent an outstanding opportunity to test our current models for nuclear matter and its properties, in particular those related to thermonuclear reactions at the surface, as well as the evolution of their ashes via weak reactions. While some aspects are relatively well understood, there are others which call out for further attention or a re-examination of what we so far know. In this talk I will discuss the current state-of-art regarding the modelling of thermal evolution of these objects and will introduce a new method aimed to simplify the calculation of thermal evolution during accreting episodes.

会場: via Zoom

イベント公式言語: 英語

Gravity is Different - Counterexamples to the Wilsonian Paradigm of Low Effective Theory

2025年7月18日(金) 14:00 - 15:30

大栗 博司 (Fred Kavli Professor and Director, Walter Burke Institute for Theoretical Physics, California Institute of Technology, USA)

As the 7th meeting of the Mathematical Application Research Team, we invite Prof. Hirosi Ooguri to give a lecture.

会場: via Zoom / セミナー室 (359号室) 3階 359号室

イベント公式言語: 英語

Modeling form growth in curved spaces using Riemannian L-systems

2025年7月17日(木) 16:00 - 17:30

Christophe Godin (Research Derector, Inria, Univ Lyon, France)

In the past 50 years, the formalism of L-systems has been successfully used and developed to model the growth of filamentous and branching biological forms. These simulations take place in classical 2-D or 3-D Euclidean spaces. However, various biological forms actually grow in curved, non-Euclidean, spaces. This is for example the case of vein networks growing within curved leaf blades, of unicellular filaments, such as pollen tubes, growing on curved surfaces to fertilize distant ovules, of teeth patterns growing on folded epithelia of animals, of diffusion of chemical or mechanical signals at the surface of plant or animal tissues, etc. In this talk, I will describe how we extended the formalism of L-systems to model the growth of branching structures in curved spaces. We will discuss how the space may feedback on the growing form and contribute to shape. I will also look at examples, where the space in which the form is growing is not necessarily a surface embedded in the euclidean 3-dimensional space, but is rather a space intrinsically curved, i.e. curved but not embedded in any higher-dimensional space. The possibility to use these more abstract Riemannian spaces potentially opens new avenues for formalizing rules driving the morphogenesis of living forms.

会場: via Zoom / SUURI-COOL (Kyushu)

イベント公式言語: 英語

Self-organization mechanism of adaptive colony size sensing in ants

2025年7月17日(木) 13:00 - 14:00

辻 瑞樹 (Professor, Department of Environmental Sciences and Technology, University of the Ryukyus)

Social insects such as ants and termites are superorganisms, and traits of a colony change in a manner similar to the growth of an individual. The most common pattern is that reproductive castes are produced only when the colony size exceeds a certain threshold, which is well known to be adaptive. This means that social insects can “sense” their own colony size. However, how they achieve this even without visual information in a dark environment was yet largely unknown. We empirically tested the self-organization hypothesis on the proximate mechanism using ant colonies. In Diacamma colonies the monogynous queen is known to increase the effort devoted to queen pheromone–transmission behaviour (patrolling) as the colony grows, as if she perceives colony size. The negative feedback hypothesis assumes that through repeated physical contacts with workers the queen monitors the physiological state (fertility) of workers and increases her patrolling effort when she encounters more fertile workers. Supporting this hypothesis, we found that queens increased patrol effort in response to a higher ratio of fertile workers under the experimental condition of constant colony size. Furthermore, supplementary experiments suggested that cuticular hydrocarbons can mediate the observed queen–worker communication of fertility state. However, when the colony size exceeds a certain value, information transmission fails, resulting in the production of the next generation of reproductive caste. Such a self-organising mechanism of sensing colony size may also operate in other social insects living in small colonies.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語