Volume 357
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Seminar Report
iTHEMS Theoretical Physics Seminar by Masashi Kawahira on May 27, 2025
2025-05-27
On May 27, Mr. Masashi Kawahira gave a seminar hosted by RIKEN iTHEMS. His talk focused on generalized symmetry and quantum symmetry from Type IIB superstring theory. Recently, generalized symmetries have enabled the systematic analysis of various quantum systems. He discussed global generalized symmetries that appear in the low-energy effective theory of type IIB superstring theory, specifically type IIB supergravity. Specifically, his work is related to the SL(2,ℤ) gauge symmetry (self-duality) in type IIB supergravity. He demonstrated that a global ℤ₁₂ eight-form symmetry emerges as the quantum symmetry of the SL(2,ℤ) gauge symmetry, along with its topological operator and its connection to 7-branes.
Reported by Okuto Morikawa
Generalized symmetry from Type IIB superstring theory
May 27 (Tue) 16:00 - 17:00, 2025
Seminar Report
Quantum Computation SG Seminar by Alberto Nocera on May 23, 2025
2025-05-26
On May 23, 2025, the Quantum Computation Study Group hosted a seminar featuring Dr. Alberto Nocera, an author on the recent Science publication that propelled D-Wave’s quantum annealer into the international spotlight. This event was held online and attracted approximately 30 participants, who engaged actively throughout the session.
Dr. Nocera delivered a highly pedagogical talk introducing the D-Wave quantum annealer and its unique approach to quantum simulation. One of the highlights of his presentation was a clear explanation of why, given the short coherence time in D-Wave’s devices, quantum states cannot adiabatically evolve. Instead, a quench of the quantum states is essential, which presents major simulation challenges for classical computers—especially at large scales. In contrast, D-Wave’s quantum annealer demonstrates the capacity to efficiently scale up such quantum quenches.
The seminar was highly interactive, with numerous questions raised both during and after the presentation. The lively Q&A underscored the community’s keen interest in the future of quantum simulation and the practical capabilities of current quantum hardware.
Overall, Dr. Nocera’s talk provided valuable insights into the rapidly evolving landscape of quantum computation and demonstrated the vital role of quantum annealers in tackling problems beyond the reach of classical computing.
Reported by Ching-Kai Chiu and Shunji Matsuura
Beyond-classical simulations using a quantum annealer
May 23 (Fri) 10:00 - 11:15, 2025
Upcoming Events
Seminar
RIKEN Quantum Seminar
Extracting particle mass on quantum computers: state preparation and measurement
June 3 (Tue) 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.
References
- Xiaoyang Wang, Long Xiong, Xiaoxia Cai, Xiao Yuan, Computing n-time correlation functions without ancilla qubits, arXiv: 2504.12975
- Xiaoyang Wang, Yuexin Su, Tongyang Li, Performance guarantees of light-cone variational quantum algorithms for the maximum cut problem, arXiv: 2504.12896
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
DEEP-IN Seminar
Solving Inverse Problems with Physics-Driven Deep Learning
June 4 (Wed) 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.
Reference
- G. Aarts, K. Fukushima, T. Hatsuda, A. Ipp, S. Shi, L. Wang, and K. Zhou, Physics-Driven Learning for Inverse Problems in Quantum Chromodynamics, Nat. Rev. Phys. Vol. 7, 154 (2025), doi: 10.1038/s42254-024-00798-x
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Biology Seminar
Mathematics of (bio)diversity and dimensionality
June 5 (Thu) 13:00 - 14:00, 2025
Seminar
iTHEMS Theoretical Physics Seminar
A New Measure of Genuine Multipartite Entanglement
June 6 (Fri) 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, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
iTHEMS Seminar
Quantum Decryption from technological perspective to business opportunities
June 6 (Fri) 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, RIKEN Wako Campus
Event Official Language: English
Seminar
DEEP-IN Seminar
Collective Behaviors and Deep Learning Applications
June 11 (Wed) 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.
References
- S. Zhou, R. Shi, and L. Wang, Extracting macroscopic quantities in crowd behaviour with deep learning, Phys. Scr. 99, 065213 (2024), doi: 10.1088/1402-4896/ad423e
- H. Hou and L. Wang, Measuring Dynamics in Evacuation Behaviour with Deep Learning, Entropy 24, 198 (2022), doi: 10.3390/e24020198
- L. Wang and Y. Jiang, Escape dynamics based on bounded rationality, Physica A 531, 121777 (2019), doi: 10.1016/j.physa.2019.121777
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Biology Seminar
Inferring Castration Status and Age-at-Death from Sheepskin Parchments
June 12 (Thu) 13:00 - 14:00, 2025
Ciarán O'Connor (Ph.D. Student, Department of Genetics, Trinity College Dublin, Ireland)
Secondary products such as traction from cattle, wool from sheep, and mobility from horses are invaluable outputs from rearing livestock. The innovative herd management practice of castration enables non-breeding males to be managed safely beyond typical ages of slaughter, greatly improving the productivity of livestock herds. Although osteological methods can identify some morphological differences between castrated and intact males, it is difficult to make clear distinctions between them. However, methylation values are affected by the considerable hormonal changes that occur as a result of castration. For example, castrated male sheep have shown lower biological ages compared to age-matched intact rams (Sugrue et al., 2021). Furthermore, age-at-death has been predicted from reconstructed methylation values in ancient horses, informing on culling practices (Liu et al., 2023). Using an aDNA-specific bisulfite sequencing approach, we have reconstructed CpG methylation values from sheepskin parchments. We have developed machine learning models trained on modern sheep in order to infer traits of interest such as castration and age-at-death. The informative CpG sites have been incorporated into a target capture set to enable cost-effective sequencing of additional samples. This will enable the characterisation of these traits in ancient sheep across time periods, geographical locations, and archaeological contexts.
References
- Sugrue, V.J., Zoller, J.A., Narayan, P., Lu, A.T., Ortega-Recalde, O.J., Grant, M.J., Bawden, C.S., Rudiger, S.R., Haghani, A., Bond, D.M. and Hore, R.R., Castration delays epigenetic aging and feminizes DNA methylation at androgen-regulated loci, Elife, 10, p.e64932. (2021), doi: 10.7554/eLife.64932
- Liu, X., Seguin-Orlando, A., Chauvey, L., Tressières, G., Schiavinato, S., Tonasso-Calvière, L., Aury, J.M., Perdereau, A., Wagner, S., Clavel, P. and Estrada, O., DNA methylation-based profiling of horse archaeological remains for age-at-death and castration, iScience, 26(3). (2023), doi: 10.1016/j.isci.2023.106144
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
ABBL-iTHEMS Joint Astro Seminar
From Galaxies to Cosmological Structures: The Multi-Scale Influence of Cosmic Rays
June 13 (Fri) 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, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
iTHEMS Theoretical Physics Seminar
A New Holographic Entanglement Entropy in the de Sitter space
June 13 (Fri) 16:00 - 17:00, 2025
Yuki Suzuki (Ph.D. Student, Yukawa Institute for Theoretical Physics, Kyoto University)
We propose a new holographic entanglement entropy in the three-dimensional de Sitter space. It is known that the holographic entanglement entropy via Ryu-Takayanagi prescription violates the entropic inequalities that they should satisfy. We propose a kind of extensions of the Ryu-Takayanagi formula so that they satisfy the strong subadditivity. We fix consistent parameter regions of the entropy and finally comment on the implications to the static patch holography.
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
DEEP-IN Seminar
Identifying Lightning Structures and Predicting Cloud Properties
June 18 (Wed) 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.
References
- L. Wang, B. M. Hare, K. Zhou, H. Stoecker, and O. Scholten, Identifying lightning structures via machine learning, Chaos, Solitons & Fractals 170, 113346 (2023), doi: 10.1016/j.chaos.2023.113346
- H. Xiao, F. Zhang, L. Wang, W. Li, B. Guo, and J. Li, CloudDiff: Super-Resolution Ensemble Retrieval of Cloud Properties for All Day Using the Generative Diffusion Model, (2024), arXiv: 2405.04483
- H. Xiao, F. Zhang, R. Zhang, F. Lu, M. Cai, and L. Wang, Retrieval of total precipitable water under all-weather conditions from Himawari-8/AHI observations using the generative diffusion model, (2025), doi: 10.22541/au.173748287.72657559/v1
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Biology Seminar
Programmed chromosome eliminations in flies
June 19 (Thu) 13:00 - 14:00, 2025
Robert Baird (Visiting Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Species that break the traditional rules of genetics and inheritance offer perhaps some of the best opportunities to study fundamental biological questions. Sciarids (fungus gnats) are a species-rich family of flies with highly unorthodox chromosome inheritance. Asymmetric male meiotic divisions result in elimination of the paternal genome every generation, and maternally-controlled eliminations of chromosomes in the developing embryo determine offspring sex. I use a combination of genomics, population genetics, and cytogenetics to understand both the mechanisms and the evolution of this system. I will discuss how these approaches have allowed us to uncover some fascinating biology as well as tackle broader biological questions.
Venue: via Zoom / Hybrid Format (3F #359 and Zoom), Seminar Room #359, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
iTHEMS Math Seminar
Spectral flow and applications
June 23 (Mon) 14:00 - 16:00, 2025
Christopher Bourne (Associate Professor, Institute of Liberal Arts and Sciences, Nagoya University)
Given a family of symmetric matrices indexed by a parameter (e.g. time, external field), changing this parameter will cause the eigenvalues to move along the real axis. The spectral flow tracks these eigenvalues and counts how many cross the point 0. This idea turns out to be very useful for both pure mathematics as well as applications to physics and elsewhere. In this talk, I will introduce the spectral flow and how it can be generalised to a variety of settings that are also relevant for applications in quantum physics.
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building, RIKEN Wako Campus / via Zoom
Event Official Language: English
Seminar
LLM-based physics analysis assistant at BESIII
June 23 (Mon) 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.
Reference
- Zhengde Zhang, Yiyu Zhang, Haodong Yao, Jianwen Luo, Rui Zhao, Bo Huang, Jiameng Zhao, Yipu Liao, Ke Li, Lina Zhao, Jun Cao, Fazhi Qi, Changzheng Yuan, Xiwu: A Basis Flexible and Learnable LLM for High Energy Physics, (2024), arXiv: 2404.08001
Venue: #345-347, Main Research Building, RIKEN Wako Campus / via Zoom
Event Official Language: English
Workshop
iTHEMS-TheoryCenter(KEK) Scientific Writing and DEI Workshop
June 24 (Tue) - 25 (Wed) 2025
Ashleigh Griffin (Professor, Department of Biology, University of Oxford, UK)
Stuart West (Professor, Department of Biology, University of Oxford, UK)
Ryosuke Iritani (Senior Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
This is a two-day KEK-iTHEMS workshop on scientific writing and diversity, equity, and inclusion.
For more details, please visit the workshop website via the relevant link.
Venue: 2F Large Conference Room, Administrative Headquarters, RIKEN Wako Campus
Event Official Language: English
Seminar
ComSHeL Seminar
ComSHeL introductions meeting
June 24 (Tue) 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, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
DEEP-IN Seminar
Generative Models for Statistical Field Theories
June 25 (Wed) 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.
References
- Q. Zhu, G. Aarts, W. Wang, K. Zhou, and L. Wang, Physics-Conditioned Diffusion Models for Lattice Gauge Theory, (2025), arXiv: 2502.05504
- L. Wang, G. Aarts, and K. Zhou, Diffusion models as stochastic quantization in lattice field theory, JHEP 05, 060 (2024), doi: 10.1007/JHEP05(2024)060
- T. Xu, L. Wang, L. He, K. Zhou, and Y. Jiang, Building imaginary-time thermal filed theory with artificial neural networks, Chin. Phys. C 48, 103101 (2024), doi: 10.1088/1674-1137/ad5f80
- S. Chen, O. Savchuk, S. Zheng, B. Chen, H. Stoecker, L. Wang, and K. Zhou, Fourier-flow model generating Feynman paths, Phys. Rev. D 107, 056001 (2023), doi: 10.1103/PhysRevD.107.056001
- L. Wang, Y. Jiang, L. He, and K. Zhou, Continuous-mixture autoregressive networks learning the Kosterlitz-Thouless transition, Chin. Phys. Lett. 39, 120502 (2022), doi: 10.1088/0256-307X/39/12/120502
Venue: #345-347, Main Research Building, RIKEN Wako Campus / via Zoom
Event Official Language: English
Seminar
iTHEMS Biology Seminar
Simulating the spread of infection in networks with quantum computers
June 26 (Thu) 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.
Reference
- X. Wang, Y. Lyu, C. Yao, and X. Yuan, Simulating the Spread of Infection in Networks with Quantum Computers, Phys. Rev. Applied (2023), doi: 10.1103/PhysRevApplied.19.064035
Venue: via Zoom / Seminar Room #359, 3F Main Research Building, RIKEN
Event Official Language: English
Seminar
Math-Phys Seminar
Exact WKB as unified analytic structure for resonance physics
June 27 (Fri) 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, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Theoretical Physics Seminar
Boundary Scattering and Non-invertible Symmetries in 1+1 Dimensions
July 4 (Fri) 14:00 - 15:00, 2025
Soichiro Shimamori (Ph.D. Student, Graduate School of Science, 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: Hybrid Format (3F #359 and Zoom), Seminar Room #359, 3F Main Research Building, RIKEN
Event Official Language: English
External Event
What is “Quantum”!?: RIKEN Symposium Commemorating 100 Years of Quantum Science
July 12 (Sat) 13:00 - 17:00, 2025
Makoto Kobayashi (Director Emeritus, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University)
Yasunori Nomura (Professor/Director, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA)
Kenji Ito (Professor, Division of Contemporary Culture, Graduate School of Letters, Kyoto University)
Miho Hatanaka (Professor, Department of Chemistry, Faculty of Science and Technology, Keio University)
Norio Kawakami (Deputy Director, Fundamental Quantum Science Program, TRIP Headquarters, RIKEN)
Yasushi Okada (Deputy Director, RIKEN Center for Biosystems Dynamics Research (BDR))
Kouichi Hagino (Professor, Graduate School of Science, Kyoto University)
Shigeki Takeuchi (Professor, Graduate School of Engineering, Kyoto University)
Yasunobu Nakamura (Director, RIKEN Center for Quantum Computing (RQC))
Makoto Gonokami (President, RIKEN)
In celebration of the 100th anniversary of the birth of quantum science, the United Nations General Assembly has declared 2025 as the International Year of Quantum Science and Technology, coordinated by UNESCO.
To mark this occasion, we will host a public symposium entitled:
“What is “Quantum”!?: RIKEN Symposium Commemorating 100 Years of Quantum Science”, aimed at the general public.
The talks will be conducted in Japanese.
For more details and to register, please visit the official website via the related link.
Venue: via Zoom
Event Official Language: Japanese
Workshop
Co-hosted by iTHEMS
The Theory of Periodic Tangles & Their Interdisciplinary Applications
July 28 (Mon) - August 1 (Fri) 2025
The mathematical characterization of entanglement holds immense potential for describing the mechanical functions of diverse physical systems and materials. A universal interdisciplinary study, involving scientists, engineers, and artists promises both advance of the field itself and significant contribution to the research and design of innovative solutions for textiles, medical devices, polymers, molecular chemistry, or construction materials among others. The program seeks an alternative to the trial–and–error approach, bringing together academia and industry to seek new sustainable solutions and inspiration, contributing to society. It will consist not only of scientific exchanges but will promote cultural impact by organizing exhibitions or hands–on workshops. Additionally, it will encourage several discussions by providing networking opportunities and utilizing the unique venue of House of Creativity at Tohoku University.
This workshop will gather researchers from various disciplines and include invited lectures, a poster session, roundtable discussions, and brainstorming activities. Our focus will be on exploring the connections between knot theory and its applications in areas such as polymers and soft matter, textile mechanics, graphic design, and more.
This event includes a joint symposium between the WPI–AIMR (Tohoku University) and WPI–SKCM2 (Hiroshima University) on Friday, August 1st, 2025: INTERWOVEN: A WPI–AIMR & WPI–SKCM2 Symposium, Towards a Universal Topological Model of Entangled Structures for Sustainable Metamaterials
Please fill in the registration form by June 16th 2025.
Confirmed speakers (alphabetical order):
Jörn Dunkel (Massachusetts Institute of Technology)
Yuanyuan Guo (Tohoku University)
Tatsuki Hayama (Keio University)
Louis H. Kauffman (University of Illinois at Chicago)
Yuka Kotorii (Hiroshima University)
Sofia Lambropoulou (National Technical University of Athens)
Eleni Panagiotou (Arizona State University)
Pedro M. Reis (École Polytechnique Fédérale de Lausanne)
Takahiro Sakaue (Aoyama Gakuin University)
Vanessa Sanchez (Rice University)
Henry Segerman (Oklahoma State University)
Koya Shimokawa (Ochanomizu University)
Hiroshi Suito (Tohoku University)
Ryuichi Tarumi (Osaka University)
Hirofumi Wada (Ritsumeikan University)
Please refer to the workshop website via the relevant link for more details.
We are looking forward to your participation and to welcoming you to Sendai!
Venue: TOKYO ELECTRON House of Creativity, Katahira Campus, Tohoku University
Event Official Language: English
Workshop
Recent Developments and Challenges in Tensor Networks: Algorithms, Applications to science, and Rigorous theories
July 28 (Mon) - August 8 (Fri) 2025
Venue: Panasonic Hall, Yukawa Institute for Theoretical Physics, Kyoto University
Event Official Language: English
Colloquium
iTHEMS Colloquium
Chemical and isotopic analyses of samples returned by the Hayabusa2 mission from the asteroid Ryugu
August 1 (Fri) 14:00 - 15:30, 2025
Tetsuya Yokoyama (Professor, Department of Earth and Planetary Sciences, School of Science, Institute of Science Tokyo)
The recent success of asteroid sample return missions has led to significant advances in Solar System science. JAXA's Hayabusa2 successfully retrieved and returned to Earth a total of 5.4 grams of samples from the C-type asteroid Ryugu. Sample return missions are critical to the scientific community, as they provide pristine, terrestrially unaltered extraterrestrial material. The analytical data obtained in laboratories for samples collected by space missions will facilitate the understanding of the formation and evolution of the Solar System. I was appointed deputy leader of the Initial Analysis Chemistry team of Hayabusa2 project, and was heavily involved in analyzing the chemical and isotopic compositions of Ryugu materials. A series of analyses of these samples indicated that the mineral, chemical, and isotopic compositions of Ryugu bear a strong resemblance to those of the Ivuna-type (CI) carbonaceous chondrites. CI chondrites have been recognized as a unique group of meteorites with a chemical composition similar to that of the solar photosphere except for highly volatile elements and Li. In the seminar, I will present the meaning and significance of the compositional similarity between Ryugu and CI chondrites. I will also present our recent activities in a new project called the Ryugu Reference Project, which was initiated to maximize the potential value of the returned samples.
Venue: 2F Large Conference Room, Administrative Headquarters, RIKEN Wako Campus / via Zoom
Event Official Language: English
Workshop
iTHEMS-NCTS Workshop
August 18 (Mon) - 21 (Thu) 2025
This workshop aims to strengthen collaboration between researchers at RIKEN iTHEMS and the National Center for Theoretical Sciences in Taiwan. It will be a four-day event, with the first two days dedicated to interdisciplinary topics. The last two days will focus on specialized areas, with one day devoted to condensed matter physics and the other to high-energy physics, including quantum gravity.
Venue: via Zoom / RIKEN Wako Campus
Event Official Language: English
Conference
Supported by iTHEMS
XIIIth International Symposium on Nuclear Symmetry Energy (NuSym25)
September 8 (Mon) - 13 (Sat) 2025
[Scientific scope]
The symposium will address experimental and theoretical investigations of the equation-of-state (EoS) of nuclear matter at various isospin asymmetries. Such investigations include efforts in nuclear structure, nuclear reactions and heavy-ion collisions, as well as in astrophysical observations of compact stars and associated phenomena. An important role of the symposium is to unify efforts of the nuclear physics and astrophysics communities in addressing common research challenges.
Venue: Integrated Innovation Building (IIB), Kobe Campus, RIKEN
Event Official Language: English
Person of the Week
Self-introduction: Chi-Kang Chang
2025-05-26
My research field is algebraic geometry, with a particular focus on birational geometry. Before joining RIKEN iTHEMS, I was a postdoctoral researcher at the National Center for Theoretical Sciences (NCTS) in Taiwan for about nine months.
I completed all of my undergraduate, master's, and doctoral studies in the Department of Mathematics at National Taiwan University. During my doctoral studies, I also spent about 14 months as a visiting research associate at the Graduate School of Mathematical Sciences, the University of Tokyo.
Paper of the Week
Week 5, May 2025
2025-05-29
Title: Incorporating episodic memory into quantum models of judgment and decision
Author: Jerome R. Busemeyer, Masanao Ozawa, Emmanuel M. Pothos, Naotsugu Tsuchiya
arXiv: http://arxiv.org/abs/2505.21521v1
Title: Nonperturbative Quantum Gravity in a Closed Lorentzian Universe
Author: Yasunori Nomura, Tomonori Ugajin
arXiv: http://arxiv.org/abs/2505.20390v1
Title: Parametrized Tidal Dissipation Numbers of Non-rotating Black Holes
Author: Hajime Kobayashi, Shinji Mukohyama, Naritaka Oshita, Kazufumi Takahashi, Vicharit Yingcharoenrat
arXiv: http://arxiv.org/abs/2505.19725v1
Title: Notes on Rindler wave packets in Minkowski spacetime
Author: Shono Shibuya, Sotaro Sugishita
arXiv: http://arxiv.org/abs/2505.20078v1
Title: Emergence of new oscillation modes in dark matter admixed neutron stars
Author: Hajime Sotani, Ankit Kumar
arXiv: http://arxiv.org/abs/2505.18800v1
Title: Time-dependent Hole States in Multiconfigurational Time-Dependent Hartree-Fock Approaches: Applications in Photoionization of Water Molecule
Author: Zhao-Han Zhang, Yang Li, Himadri Pathak, Takeshi Sato, Kenichi L. Ishikawa, Feng He
arXiv: http://arxiv.org/abs/2505.11319v1
Title: Time-dependent Hole States in Multiconfigurational Time-Dependent Hartree-Fock Approaches: A Time-Domain Generalization of Extended Koopmans' Theorem
Author: Zhao-Han Zhang, Yang Li, Himadri Pathak, Takeshi Sato, Kenichi L. Ishikawa, Feng He
arXiv: http://arxiv.org/abs/2505.11290v1
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