Seminar

Boundary Scattering and Non-invertible Symmetries in 1+1 Dimensions

July 4 (Fri) at 14:00 - 15:00, 2025

Soichiro Shimamori (Ph.D. Student, Osaka University)

Recent studies by Copetti, Córdova and Komatsu have revealed that when non-invertible symmetries are spontaneously broken, the conventional crossing relation of the S-matrix is modified by the effects of the corresponding topological quantum field theory (TQFT). We extend these considerations to (1+1)-dimensional quantum field theories (QFTs) with boundaries. In the presence of a boundary, one can define not only the bulk S-matrix but also the boundary S-matrix, which is subject to a consistency condition known as the boundary crossing relation. We show that when the boundary is weakly-symmetric under the non-invertible symmetry, the conventional boundary crossing relation also receives a modification due to the TQFT effects. As a concrete example of the boundary scattering, we analyze kink scattering in the gapped theory obtained from the Φ(1,3)-deformation of a minimal model. We explicitly construct the boundary S-matrix that satisfies the Ward-Takahashi identities associated with non-invertible symmetries. This talk is based on the collaboration with Satoshi Yamaguchi.

Venue: via Zoom

Event Official Language: English

Exact WKB as unified analytic structure for resonance physics

June 27 (Fri) at 15:00 - 17:00, 2025

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

We develop a unified framework for analyzing quantum mechanical resonances using the exact WKB method. The non-perturbative formulation based on the exact WKB method works for incorporating well-established phenomenological regularizations, the ABC theorem (proof of the completeness of Hilbert space), and the rigged Hilbert space in resonant phenomena. By examining the inverted Rosen-Morse potential, we illustrate how the exact WKB analysis captures resonant phenomena rigorously. Also, we clarify the corresponding linear spaces defined in each step of the exact WKB manipulations. The complementarity between the essential analyticity for resonance and the ABC theorem leads us to construct a modified Hilbert space called the rigged Hilbert space within the exact WKB framework. This offers a deeper understanding of resonant states and their analytic structures. Our results provide a concrete demonstration of the non-perturbative accuracy of exact WKB methods in unstable quantum systems.

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

Event Official Language: English

Simulating the spread of infection in networks with quantum computers

June 26 (Thu) at 13:00 - 14:00, 2025

Xiaoyang Wang (Postdoctoral Researcher, Quantum Mathematical Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Many classical stochastic processes can be modeled as Markovian processes, including the spreading of infection in networks. Simulating the Markovian processes using classical computers is generally unscalable for large networks. In this seminar, I will introduce the Hamiltonian evolution on quantum computers and how the Markovian spreading of infection can be efficiently simulated using the Hamiltonian evolution. In particular, we analytically and numerically analyze the evolution of a specifically designed Hamiltonian, and prove that the evolution simulates a classical Markovian process, which describes the well-known epidemiological stochastic susceptible and infectious (SI) model. As an example, we simulate the infection spreading process of the SARS-CoV-2 variant Omicron in a small-world network. The simulation results are qualitative consistent with the infection spreading in the west coast of USA.

Venue: via Zoom / Seminar Room #359

Event Official Language: English

Generative Models for Statistical Field Theories

June 25 (Wed) at 15:00 - 16:00, 2025

Lingxiao Wang (Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

In the final talk of the DEEP-IN series, we will explore the role of generative models in learning phase transitions and sampling in lattice systems. First, we demonstrate how generative models can serve as global samplers by learning the underlying probability distributions. This enables the sampling of configurations more efficiently for lattice field theories. We will also demonstrate how the ferromagnetic phase transition, the Kosterlitz-Thouless transition, and quantum phase transitions can be identified from generative models. I will briefly introduce generative diffusion models, which can be interpreted as a stochastic quantization scheme. This opens a new path for understanding deep generative models. This is an informal seminar, we will start with the methodology and some practical examples, and finally reserve time for everyone interested to discuss it together.

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

Event Official Language: English

ComSHeL introductions meeting

June 24 (Tue) at 14:00 - 15:30, 2025

Following our Launch Meeting on May 1st, in this second meeting of our study group we plan for each member of the ComSHeL Study Group and anyone who joins us that day to introduce their research briefly to get to know one another's focus and expertise. If you are interested in possibly collaborating with ComSHeL members and/or you would like to get to know some of the researchers who joined us as part of iTHEMS new Division of Applied Mathematical Science, please join us. I extended the duration to 90 min (from our usual 60 min) to make sure we have enough time to hear from everyone. Each attendee will have approximately 4 minutes to explain their past, current, or upcoming research and time will be kept strictly. Time might be adjusted on the day of the meeting based on the number of applicants. If you would like to show some slides (max 3 slides), please prepare them in advance and send them to cbeau@riken.jp in PDF format no later than June 20. But no one should feel they must prepare slides: it is fine to speak freely and informally about your work.

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

Event Official Language: English

LLM-based physics analysis assistant at BESIII

June 23 (Mon) at 15:00 - 16:00, 2025

Yipu Liao (Ph.D. Student, Institute of High Energy Physics, Chinese Academy of Sciences, China)

The data processing and analyzing is one of the main challenges at HEP experiments. To accelerate the physics analysis and drive new physics discovery, the rapidly developing Large Language Model (LLM) is the most promising approach, it have demonstrated astonishing capabilities in recognition and generation of text while most parts of physics analysis can be benefitted. In this talk we will discuss the construction of a dedicated intelligent agent, an AI assistant names Dr.Sai at BESIII based on LLM, the potential usage to boost the data analysis. I will also provide a brief overview of the construction of the AI platform at the Institute of High Energy Physics (ai.ihep.ac.cn) and outline the roadmap for AI4HEP. Yipu Liao (廖一朴) is a Ph.D. student at the Institute of High Energy Physics, Chinese Academy of Sciences. His research is centered on particle physics data analysis, with a special emphasis on Charmonium(-like) and tau physics within the BESIII and Belle II experiments. He is actively engaged in the development of the AI assistant project (DrSai) for the BESIII experiment, and leads the design and evaluation of automated processes.

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

Event Official Language: English

Identifying Lightning Structures and Predicting Cloud Properties

June 18 (Wed) at 15:00 - 16:00, 2025

Lingxiao Wang (Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

This third talk in the DEEP-IN series focuses on using unsupervised machine learning to identify and predict patterns in atmospheric phenomena. We begin by demonstrating how clustering and dimensionality reduction techniques can uncover coherent lightning patterns from high-dimensional LOFAR (LOw Frequency ARray) data, offering insight into large-scale organization. We then show how generative diffusion models enable super-resolution retrieval of cloud properties for all day from satellite observations. This is an informal seminar, we will start with the methodology and some practical examples, and finally reserve time for everyone interested to discuss it together.

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

Event Official Language: English

From Galaxies to Cosmological Structures: The Multi-Scale Influence of Cosmic Rays

June 13 (Fri) at 14:00 - 15:15, 2025

Ellis Owen (Special Postdoctoral Researcher, Astrophysical Big Bang Laboratory, RIKEN Pioneering Research Institute (PRI))

Cosmic rays interact with astrophysical systems over a broad range of scales. They go hand-in-hand with violent, energetic astrophysical environments, and are an active agent able to regulate the evolution and physical conditions of galactic and circum-galactic ecosystems. Depending on their energy, cosmic rays can also escape from their galactic environments of origin, and propagate into larger-scale cosmological structures. In this talk, I will discuss the impacts of cosmic rays retained in galaxies. I will show they can deposit energy and momentum to alter the initial conditions of star-formation, modify the circulation of baryons around galaxies, and have the potential to regulate long-term galaxy evolution. I will highlight some of the astrophysical consequences of contained hadronic and leptonic cosmic rays in and around galaxies, and how their influence can be probed using signatures including X-rays, gamma-rays and neutrinos. I will also discuss what happens to the cosmic rays that escape from galaxies, including their interactions with the magnetized large-scale structures of our Universe, and the fate of distant high-energy cosmic rays that do not reach us on Earth.

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

Event Official Language: English

Collective Behaviors and Deep Learning Applications

June 11 (Wed) at 15:00 - 16:00, 2025

Lingxiao Wang (Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Understanding and modeling collective pedestrian behavior, particularly under extreme conditions, is a challenging problem that combines cognition, physics, and data analysis. In the second talk of DEEP-IN series, I will explore how deep learning can reveal the underlying principles of crowd dynamics from data. Starting with a bounded rationality framework, we demonstrate how deep learning can quantify evacuation dynamics and reveal hidden patterns in collective motion. Specifically, we demonstrate how macroscopic observables, such as entropy and kinetic energy, can be extracted from microscopic trajectories in simulations and real-world data. This is an informal seminar, we will start with the methodology and some practical examples, and finally reserve time for everyone interested to discuss it together.

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

Event Official Language: English

Quantum Decryption from technological perspective to business opportunities

June 6 (Fri) at 16:00 - 17:30, 2025

Sho Sugiura (CEO, BlocQ, Inc.)

Quantum decryption is a foundational application of fault-tolerant quantum computing (FTQC), essential for future cryptographic security. While quantum simulations, especially quantum chemistry, dominate current quantum computing research, quantum decryption remains less explored despite its significance. In this talk, we give a business style talk that overviews the current status of quantum decryption and our company's pioneering efforts to advance practical FTQC-based solutions. We discuss recent technological advancements and outline our strategic initiatives aimed at leading the field toward secure communications.

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

Event Official Language: English

A New Measure of Genuine Multipartite Entanglement

June 6 (Fri) at 14:00 - 15:00, 2025

Jaydeep Kumar Basak (Post-doctoral Fellow, Gwangju Institute of Science and Technology (GIST), Republic of Korea)

In this talk, I will introduce ``Latent entropy" (L-entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party GHZ states and $n=4,5$-party $2$-uniform states. I will also show the generalization of this measure for higher party states. Furthermore, I will discuss an analogue of the Page curve in multiboundary wormholes. If time permits, I will show the behaviour of multipartite entanglement in random states.

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

Event Official Language: English

Solving Inverse Problems with Physics-Driven Deep Learning

June 4 (Wed) at 15:00 - 16:00, 2025

Lingxiao Wang (Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

This talk kicks off a four-part seminar series on the DEEP-IN WG, an interdisciplinary working group exploring how modern deep learning — including deep generative models — can tackle inverse problems across scientific domains. In addition to DEEP-IN activities, I will present a new framework and vision, motivated by the growing synergy between physics-driven designs for deep learning and scientific discovery, as discussed in our recent review article. Future talks will demonstrate machine learning applications in collective behaviors, weather systems, and lattice field simulations. This is an informal seminar, we will start with the methodology, give some practical examples, and finally reserve time for everyone interested to discuss it together.

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

Event Official Language: English

Extracting particle mass on quantum computers: state preparation and measurement

June 3 (Tue) at 11:00 - 12:30, 2025

Xiaoyang Wang (Postdoctoral Researcher, Quantum Mathematical Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

In this seminar, I will introduce the procedure of extracting particle mass from the ab initio calculation using quantum computers, including two essential steps: state preparation and measurement. For the measurement process, in our recent work "Computing n-time correlation functions without ancilla qubits" [arXiv:2504.12975], we developed a measurement method for correlation functions without ancilla qubits, circumventing longstanding hardware constraints of limited qubit connectivity and short-range control operations. We demonstrate our method using IBM quantum hardware and successfully reproduce the noiseless results of the Schwinger model hadron mass within a relative error of 0.18%, even in the presence of realistic hardware limitations and noise. For the state preparation process, another work "Performance guarantees of light-cone variational quantum algorithms for the maximum cut problem" [arXiv:2504.12896] focused on the accuracy of the state preparation using variational quantum algorithms (VQAs). We propose a light-cone VQA with provable performance guarantees, whose single round has higher accuracy than the 3-round standard VQA for the maximum cut problem. We experimentally validated the single-round light-cone VQA using IBM quantum hardware with solution accuracy that exceeds the known classical hardness threshold in both a 72-qubit demonstration and a 148-qubit demonstration.

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

Event Official Language: English

Ecology and Evolution of Mammal-Microbe Interactions

May 29 (Thu) at 16:00 - 17:00, 2025

Taichi A Suzuki (Assitant Professor, Biodesign Center for Health Through Microbiomes, Arizona State University, USA)

A critical open question in microbiome research is identifying key host-microbial interactions that influence host fitness. While the disruption of coevolved host-microbial interactions is known to affect host fitness in simpler systems (e.g., insects and their symbionts), understanding the extent and consequences of host-microbial coevolution in more complex systems (e.g., mammals and their gut microbiota) remains a major challenge. My research has identified multiple species of gut microbes in adults and children that share a parallel evolutionary history with humans by analyzing paired human genotypes and bacterial strain genotypes. In another line of work, I applied a selection experiment demonstrating that selection and transmission of the microbiome and its metabolites can alter mouse locomotion behavior within four rounds of microbiome transfer, without any changes to the mouse genome. Finally, I will briefly outline my future plans to study the effects of disrupting evolutionary stable host-microbial associations on the phenotypes of deer mice (Peromyscus spp.) in the Madrean Sky Islands and genetically diverse human populations in Arizona. Biosketch: Assistant Professor at Arizona State University since 2023. MS at University of Arizona, PhD at University of California Berkeley, and Postdoc at Max Planck Institute for Biology. My group integrates evolutionary genomics, microbial ecology, and biomedical research to study host-microbial interactions using wild rodents and humans.

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

Event Official Language: English

Non-perturbative formulation of resonant quantum mechanics within unified exact WKB framework

May 28 (Wed) at 16:00 - 17:30, 2025

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

We study quasi-stationary states in quantum mechanics using the exact WKB analysis as a non-perturbative framework. We explore unstable states such as resonances by analyzing the inverted Rosen-Morse potential, which exhibits barrier resonance. This model allows exact solutions, enabling a direct comparison with exact WKB predictions. We provide a simple analytic picture of resonance and demonstrate consistency between exact and WKB-based results. A unified exact WKB framework is developed for exploring the equivalence and complementarity of different well-established regularizations \`a la Zel'dovich, complex scaling, and rigged Hilbert space within this framework.

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

Event Official Language: English

Generalized symmetry from Type IIB superstring theory

May 27 (Tue) at 16:00 - 17:00, 2025

Masashi Kawahira (Postdoctoral Fellow, Department of Physics, Graduate School of Science, Kobe University)

Recently, generalized symmetries have enabled the systematic analysis of various quantum systems. In this talk, we focus on global generalized symmetries that appear in the low-energy effective theory of type IIB superstring theory (i.e., type IIB supergravity). Specifically, we highlight the SL(2,ℤ) gauge symmetry (self-duality) in type IIB supergravity. We see that a global ℤ₁₂ eight-form symmetry arises as the quantum symmetry of the SL(2,ℤ) gauge symmetry. And we discuss its topological operator and its relation to 7-branes. This talk is based on joint work with Hiroki Wada (Tohoku University) and Naoto Kan (Osaka University).

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

Event Official Language: English

A review of incompatibility in quantum information science (Topical Review Meeting #1)

May 26 (Mon) at 16:00 - 17:30, 2025

Haruki Emori (Junior Research Associate, Quantum Mathematical Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

As the first activity of the Quantum Foundation Study Group, we will hold a Topical Review Meeting. In quantum mechanics and quantum information science, the exploration of “quantumness” is of fundamental importance. One key concept that captures quantumness is “incompatibility”. In this meeting, I will give a review on incompatibility. If time permits, I would also like to introduce some of my recent research on this topic and engage in discussions with the participants.

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

Event Official Language: English

SISSI: Supernovae in a Shearing, Stratified Interstellar Medium

May 23 (Fri) at 14:00 - 15:15, 2025

Leonard Romano (Ph.D. Student, Ludwig-Maximilians-Universität München, Germany)

Supernovae (SNe) are an important driver of the multiphase structure in the Interstellar Medium (ISM) and play an important role for regulating star formation. SNe inflate large bubbles of hot gas dubbed Supernova Remnants (SNRs) that can remain hot for several 10⁵-10⁶ years, contributing substantially to the volume filling hot phase, galactic outflows and the driving of turbulence in the ISM. In this talk, I am presenting the results of zoom-in simulations of SNRs embedded in a simulated isolated Milky-Way analogue, in order to investigate how environmental effects like shear, vertical stratification and a self-consistently generated ISM can affect various properties of SNRs. I find that initially microscopic SNRs, whose dynamics are dominated by local shock physics, after a few Myr enter a mesoscopic regime, where their dynamics are increasingly dominated by galactic scale processes. Based on these findings, I make predictions about SN-driven large-scale structure, such as galactic outflows and the geometry of large superbubbles in disk galaxies.

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

Event Official Language: English

Beyond-classical simulations using a quantum annealer

May 23 (Fri) at 10:00 - 11:15, 2025

Alberto Nocera (Senior Staff Scientist, Stewart Blusson Quantum Matter Institute, The University of British Columbia, Canada)

Join us for an electrifying online zoom talk featuring Dr. Alberto Nocera, the author of the groundbreaking Science article detailing D-Wave's quantum annealer outperforming classical supercomputers in simulating complex magnetic materials. D-Wave’s quantum annealer uses quantum annealing to efficiently solve optimization problems by finding low-energy states of complex systems. Unlike IBM and Quantinuum’s gate-based quantum computers, which are universal and execute algorithms via quantum circuits, D-Wave’s system is specialized but currently more scalable and practical for certain applications. While gate-based systems are still limited by noise and error rates, D-Wave’s annealer recently demonstrated a quantum advantage in simulating magnetic materials, outperforming classical supercomputers. This highlights a key difference: D-Wave excels in specific tasks today, while IBM and Quantinuum aim for broader, long-term quantum computational capabilities. Talk Abstract: Solving the equations governing the dynamics of interacting many-particle quantum systems is one of the biggest challenges in modern science. In 1982, Richard P. Feynman envisioned that the best way to emulate the behavior of many-particle quantum systems is to use another quantum system, starting the field of quantum simulation. Rather than seeking to solve the fundamental equations of quantum mechanics using conventional or classical computers, in quantum simulation one seeks to simulate a quantum system using an "analog device" mimicking its behavior, hoping to access solutions which are not easy to compute otherwise. In this talk, using the quantum annealing simulator device developed by D-Wave as a main tool, I will show that the use of tensor network methods has a key role in quantum simulation: besides benchmarking the quantum device, they can assess and help establishing its functionality beyond the classically simulatable regime [1].

Venue: via Zoom

Event Official Language: English