Volume 345
Back to Newsletter List

Hot Topic
RIKEN-Nara Women's University Joint Diversity Promotion Workshop 2025 on March 3, 2025
2025-03-06
On March 3 and 4, a total of 19 students from various courses at Nara Women's University—including mathematics, physics, chemistry, biological sciences, and environmental sciences (comprising first-year, second-year, and third-year undergraduate students, as well as first-year master's students)—visited RIKEN. During their visit, they toured several research facilities, including the RIBF Facility at the RIKEN Nishina Center (RNC), the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), the Laboratory for Sensorimotor Integration at the RIKEN Center for Brain Science (CBS), the Photonics Control Technology Team at the RIKEN Center for Advanced Photonics (RAP), and the Molecular Bioregulation Research Team at the RIKEN Center for Sustainable Resource Science (CSRS).
At each laboratory, the students had the opportunity to engage with cutting-edge research up close, observe experimental equipment, and ask researchers about their work. In the evening, they participated in a networking session with RIKEN researchers, where they explored research topics in depth through iTHEMS members' poster presentations. This interactive session also provided insights into the daily lives and career paths of researchers, offering students valuable inspiration from the research environment.
This diversity promotion initiative is a collaborative project between the Faculty of Science at Nara Women's University and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), conducted under the auspices of the RIKEN Diversity Promotion Office. It is organized alongside a series of lectures at Nara Women's University and is planned to continue in the coming years.
RIKEN-Nara Women's University Joint Diversity Promotion Workshop 2025
March 3 (Mon) - 4 (Tue), 2025
Research News
Review on Physics-Driven Learning for Inverse Problems Published in Nature Reviews Physics
2025-03-06
Nature Reviews Physics recently published a review paper on ”Physics-driven learning for inverse problems in quantum chromodynamics”, from DEEP-IN working group led by Lingxiao Wang (Research Scientist, iTHEMS), including Tetsuo Hatsuda (Program Director, iTHEMS). The authors explore how combining deep learning techniques with physics-driven designs significantly improves the extraction of accurate physical properties from complex QCD phenomena. Highlighting applications such as lattice QCD calculations and studies of hadron interactions, neutron stars, and heavy-ion collisions, the review emphasizes the benefits of embedding physical priors into machine learning models and suggests broader potentials to general physics problems.
Reference
- Gert Aarts, Kenji Fukushima, Tetsuo Hatsuda, Andreas Ipp, Shuzhe Shi, Lingxiao Wang & Kai Zhou, Physics-driven learning for inverse problems in quantum chromodynamics, Nat Rev Phys 7, 154–163 (2025), doi: 10.1038/s42254-024-00798-x
Upcoming Events
Workshop
Kyushu IAS-iTHEMS conference: Non-perturbative methods in QFT
March 10 (Mon) - 14 (Fri), 2025
The most commonly used approach in the study of QFT is perturbation theory. Indeed, we have succeeded in extracting various physical quantities from perturbative (asymptotic) expansions. However, some physical phenomena cannot be captured through perturbative analyses alone. How can we extract these non-perturbative effects?
In QFTs with conformal symmetry (i.e., CFTs), correlation functions can be computed using a method called the conformal bootstrap. This non-perturbative method differs entirely from the usual correlation function analysis methods of QFT, as it does not even assume the existence of a Lagrangian. Through the use of the conformal bootstrap, we have actually made significant progress in the non-perturbative understanding of CFTs.
Furthermore, according to the holographic principle, CFTs provide a non-perturbative formulation of QFTs with gravity (i.e., quantum gravity). By applying the holographic principle to various non-perturbative results from CFTs, such as those obtained from the conformal bootstrap, we have made remarkable advances in understanding the non-perturbative aspects of quantum gravity. Conversely, the holographic principle is also used to understand properties of QFTs that are difficult to analyze perturbatively, through gravity.
Venue: Kyushu University Ito Campus, Inamori Hall
Event Official Language: English
Conference
Meeting for Intersections of Nuclear and Other Researches
March 10 (Mon) - 11 (Tue), 2025
The purpose of this workshop (held in Japanese) is to promote interdisciplinary research by young researchers through exchanges among all fields of theoretical physics, including the nuclear physics, which is a boundary region between various fields.
Venue: #435-437, Main Research Building, RIKEN
Event Official Language: Japanese
Seminar
RIKEN Quantum Seminar
RIKEN Quantum hands-on workshop on QURI SDK for creating and executing quantum algorithms on various quantum computers and simulators
March 13 (Thu) at 15:00 - 17:30, 2025
This workshop will be a hands-on session on QURI SDK, following the RIKEN Quantum seminar by Andreas Thomasen (QunaSys) on January 27.
Even if you did not attend the previous seminar, please join us if you would like to learn how to use QURI SDK.
The workshop outline is as follows:
- General introduction to QURI SDK and its intended workflow
- Introduction to QURI VM with various virtual devices introduced
- Experimenting with surface code parameters in QURI VM
- Introduction to QURI Algo and algorithm components
- Introduction to various algorithms for early FTQC
This workshop will be a hybrid of on-site and Zoom, but we encourage you to attend on-site to learn how to use QURI SDK more clearly.
In addition to the instructor, QunaSys researchers will be available to help you directly.
The Zoom URL will be provided only to registered participants.
To participate, please fill out the registration form at the link above by March 3.
Organizers: Andreas Thomasen (QunaSys), Kentaro Wada (QunaSys), Shinichiro Fujii (RIKEN)
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Biology Seminar
It’s about time! Daily rhythms in malaria infections matter for parasite survival and transmission
March 13 (Thu) at 17:00 - 18:00, 2025
Reece Sarah (Professor, University of Edinburgh, UK)
The Reece lab provides a unique perspective on parasites, examining their world within hosts and vectors (insects that transmit parasites). Working at the intersection of parasitology, chronobiology, and evolutionary ecology, our research asks: “what makes a successful parasite” and “what are their evolutionary limits”? Unlike most infection research, that focuses solely on genetics and molecular aspects, our approach considers parasites in their ecological and evolutionary contexts. This has enabled us to uncover the sophisticated strategies that malaria parasites possess, such as optimizing the balance between transmission and replication, strategic investment in each sex of transmission stages, and scheduling activities according to the time of day. By understanding how parasites navigate their challenging lifestyles and seize opportunities, we contribute to interventions that can outsmart parasites and reduce the risk of resistance evolution. Our findings extend beyond the laboratory, showcasing the potential of environmental research to curb the impact of parasitic infections, whether in humans, wildlife, livestock, or agriculture, and helping to protect ecosystems.
Venue: via Zoom
Event Official Language: English
Seminar
Lab-Theory Standing Talks
Complexity, expressivity, syntax and semantics
March 14 (Fri) at 14:00 - 14:30, 2025
Yusaku Nishimiya (Student Trainee, Natural Language Understanding Team, RIKEN Center for Advanced Intelligence Project (AIP))
I will summarise the philosophical motivations behind two research topics; 1. complexity/computability and 2. logic (structural proof theory), and discuss how they may help us understand what makes some problems harder than others, or equivalently, some knowledge more difficult to attain than others (my broad research goals).
I. Complexity/computability
Computational complexity and computability theory are a subfield of theoretical computer science in which we mathematically study the 'hardness' of problems. We do so by classifying algorithms or a collection of pre-defined rules that some solver can apply without ingenuity by how much time and memory space they require.
II. Structural proof theory
Even whilst maintaining the basic idea that a well-formed sentence, or a proposition, is either true or false, one can still make a conscious choice about what kind of principles to permit in deriving a new statement from assumptions. Structural proof theory formalises this as a logical-deduction system to study their effect on what the logic can and cannot do.
III. What I do, more specifically
I take advantage of equivalences between some computational complexity classes and logic, the latter of which, I hope, can serve as an interface to connect, via semantics, complexity with wider mathematics to elucidate something that can tell us what makes some computation inherently costly.
IV. 'Computational view' of science
I would love to discuss if time permits, how we may apply the idea of complexity to illuminate how information transfers from one thing to another in physical, biological and social systems.
Venue: 3rd floor public space, Main Research Building, RIKEN
Event Official Language: English
Seminar
Quantum Gravity Gatherings
Asymptotically flat black hole spacetimes with multiple injections
March 14 (Fri) at 15:30 - 17:00, 2025
Yuta Saito (Ph.D. Student, Graduate School of Science and Technology, Nihon University)
In quantum gravity, Hawking radiation presents several fundamental problems. One of the problems is the black hole (BH) information paradox, in which the entanglement entropy (EE), which quantifies quantum entanglement, exceeds its upper bound. In the absence of the paradox, EE follows the Page curve. Recent progress has been made in resolving this paradox using the island formula, a method for computing EE that successfully reproduces the expected Page curve. In this approach, a portion of the black hole interior is treated as part of the radiation region.
Meanwhile, an alternative scenario has been proposed where multiple collapsing shells prevent the formation of a well-defined event horizon [1]. In this case, radiation is emitted throughout the collapse process, shifting dynamically the Schwarzschild radius inward, and a surface structure is formed just outside. This leads to a distinction between the conventional event horizon and the surface, introducing an intermediate region between the Schwarzschild radius and the surface. Interestingly, this model also suggests that part of the black hole interior effectively belongs to the radiation region, drawing a possible parallel to the island formula.
In this talk, we explore spacetimes with multiple energy injections in asymptotically flat two-dimensional black hole backgrounds and analyze the entanglement entropy in such scenarios. Since considering backreaction in gravitational collapse in two dimensions is difficult, we instead construct a spacetime solution with multiple energy injections and analyze EE within this background. The main focus of this talk is to derive the spacetime and examine its properties. Additionally, we perform EE calculations in parallel with previous studies [2], which consider the case of α single injection, and confirm that the behavior of EE depends on the interval between energy injections.
References
- H. Kawai, Y. Matsuo and Y. Yokokura, A Self-consistent Model of the Black Hole Evaporation, doi: 10.1142/S0217751X13500504
- F. F. Gautason, L. Schneiderbauer, W. Sybesma, and L. Thorlacius, Page Curve for an Evaporating Black Hole, doi: 10.1007/JHEP05(2020)091
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
ABBL-iTHEMS Joint Astro Seminar
Fast radio bursts as precursor radio emission from monster shocks
March 21 (Fri) at 16:00 - 17:15, 2025
Arno Vanthieghem (Assistant Professor, Observatoire de Paris and Sorbonne Université, France)
It has been proposed recently that the breaking of MHD waves in the inner magnetosphere of strongly magnetized neutron stars can power different types of high-energy transients. Motivated by these considerations, we study the steepening and dissipation of a strongly magnetized fast magnetosonic wave propagating in a declining background magnetic field, by means of particle-in-cell simulations that encompass MHD scales. Our analysis confirms the formation of a monster shock, that dissipates about half of the fast magnetosonic wave energy. It also reveals, for the first time, the generation of a high-frequency precursor wave by a synchrotron maser instability at the monster shock front, carrying a fraction of 0.1% of the total energy dissipated at the shock. The spectrum of the precursor wave exhibits several sharp harmonic peaks, with frequencies in the GHz band under conditions anticipated in magnetars. Such signals may appear as fast radio bursts.
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359, 3F Main Research Building, RIKEN
Event Official Language: English
Workshop
Third Workshop on Density Functional Theory: Fundamentals, Developments, and Applications (DFT2025)
March 25 (Tue) - 27 (Thu), 2025
The density functional theory (DFT) is one of the powerful methods to solve quantum many-body problems, which, in principle, gives the exact energy and density of the ground state. The accuracy of DFT is, in practice, determined by the accuracy of an energy density functional (EDF) since the exact EDF is still unknown. Currently, DFT has been used in many communities, including nuclear physics, quantum chemistry, and condensed matter physics, while the fundamental study of DFT, such as the first principle derivations of an accurate EDF and methods to calculate many observables from obtained densities and excited states, is still ongoing. However, there has been little opportunity to have interdisciplinary communication.
On December 2022, we had the first workshop on this series (DFT2022) at Yukawa Institute for Theoretical Physics, Kyoto University, and several interdisciplinary discussions and collaborations were started. On February 2024, we had the second workshop on this series (DFT2024) at RIKEN Kobe Campus, and more stimulated discussion occured. To keep and extend collaborations, we organize the third workshop. Since the third workshop, we extend the scope of the workshop to the development and application of DFT as well. In this workshop, the current status and issues of each discipline will be shared towards solving these problems by meeting together among researchers in mathematics, nuclear physics, quantum chemistry, and condensed matter physics.
This workshop mainly comprises lectures/seminars on cutting-edge topics and discussion, while sessions composed of contributed talks are also planned.
Venue: 8F, Integrated Innovation Building (IIB), Kobe Campus, RIKEN / via Zoom
Event Official Language: English
Seminar
Quantum Gravity Gatherings
Stability of nonsingular black holes
March 27 (Thu) at 15:00 - 16:30, 2025
Shinji Tsujikawa (Professor, Graduate School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University)
We show that nonsingular black holes (BHs) realized in nonlinear electrodynamics are always prone to Laplacian instability around the center because of a negative squared sound speed in the angular direction. This is the case for both electric and magnetic BHs, where the instability of one of the vector-field perturbations leads to enhancing a dynamical gravitational perturbation in the even-parity sector. Thus, the background regular metric is no longer maintained in a steady state. We also generalize our analysis to the case in which a scalar field is present besides the U(1) gauge field and find no explicit examples of linearly stable nonsingular BHs. Our results suggest that the construction of regular BHs without instabilities is generally challenging within the scheme of classical field theories.
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Biology Seminar
The rarer-sex effect
March 27 (Thu) at 16:00 - 17:00, 2025
Andy Gardner (Professor, School of Biology, University of St Andrews, UK)
The study of sex allocation—that is, the investment of resources into male versus female reproductive effort—yields among the best quantitative evidence for Darwinian adaptation, and has long enjoyed a tight and productive interplay of theoretical and empirical research. The fitness consequences of an individual's sex allocation decisions depend crucially upon the sex allocation behaviour of others and, accordingly, sex allocation is readily conceptualized in terms of an evolutionary game. I will discuss the historical development of understanding of a fundamental driver of the evolution of sex allocation—the rarer-sex effect—from its inception in the writing of Charles Darwin in 1871 through to its explicit framing in terms of consanguinity and reproductive value by William D. Hamilton in 1972. I will show that step-wise development of theory proceeded through refinements in the conceptualization of the strategy set, the payoff function and the unbeatable strategy.
Venue: #445-447, 4F (Hybrid), Main Research Building, RIKEN / via Zoom
Event Official Language: English
Seminar
iTHEMS Seminar
Artificial Intelligence and Neuroscience
April 11 (Fri) at 14:00 - 15:30, 2025
Junichi Chikazoe (Professor, Center for Brain,Mind and KANSEI Sciences Research, Hiroshima University)
Recent advancements in artificial intelligence have led to various discoveries in the field of neuroscience. For example, it has been demonstrated that the information on orientation columns in the visual cortex and the basic taste information in the gustatory cortex can be extracted by applying machine learning to relatively low-resolution functional MRI data. Additionally, intriguing findings have emerged, such as the information processing structures of artificial neural circuits—designed independently of the brain—showing similarities to those of biological neural networks.
In this talk, I will discuss the applications of artificial intelligence in neuroscience and explore future directions in this field.
Venue: Seminar Room #359, 3F Main Research Building, RIKEN / via Zoom
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) 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, 3F Main Research Building, RIKEN
Event Official Language: English
Paper of the Week
Week 2, March 2025
2025-03-06
Title: Collective Neutrino Oscillations in Three Flavors on Qubit and Qutrit Processors
Author: Luca Spagnoli, Noah Goss, Alessandro Roggero, Ermal Rrapaj, Michael J. Cervia, Amol V. Patwardhan, Ravi K. Naik, A. Baha Balantekin, Ed Younis, David I. Santiago, Irfan Siddiqi, Sheakha Aldaihan
arXiv: 2503.00607
If you would like to cancel your subscription or change your email address,
please let us know via our contact form.
Copyright © iTHEMS, RIKEN. All rights reserved.