Featured News
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RIKEN Research: Flitting between the wings of a butterfly
Just making small tweaks to certain variables could potentially modify extreme weather events such as sudden downpours, computer simula- tions by two RIKEN researchers have shown. Scientists have long desired to develop ways to control the weather. Research in this area has intensified due to climate change, which is giving rise to more extreme weather events. Present methods for modifying the weather have limited success. Seeding the atmosphere can induce rain, but only when the atmosphere is already in a state where it might rain. Geoen- gineering projects have been envisioned, but they have yet to be conducted due to concerns about unpredicted long-term effects. As a promising approach, Takemasa Miyoshi and Qiwen Sun, both of the RIKEN Center for Computational Science, have looked to chaos theory to assess the possibility of mitigating weather events such as torrential rain by making small changes. Instead of con- sidering the weather system in all its complexity, they focused on a far simpler system—the butterfly attractor. To read more, please see related links.
2022-06-28
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RIKEN Research: Worming out of the black-hole information paradox
RIKEN physicist and two colleagues have found that a wormhole—a theoretical bridge connecting distant regions of the Universe—may help to shed light on the mystery of what happens to information about matter consumed by black holes. Einstein’s theory of general relativity predicts that nothing that falls into a black hole can escape its clutches. But in the 1970s, Stephen Hawking calculated that black holes should emit radiation when quantum mechanics, the theory governing the microscopic realm, is considered. “This is called black hole evaporation because the black hole shrinks, just like an evaporating water droplet,” explains Kanato Goto of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences. To read more, please see related links.
2022-06-28
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RIKEN-Berkeley Center was opened
RIKEN iTHEMS and N3AS Physics Frontier Center have started a joint research center, RIKEN-Berkeley Center (RBC), physically located on the 3rd floor of the physics building in Univ. California, Berkeley. This new Center aims to enhance the collaboration on nuclear astrophysics and quantum information science between the two institutions. On May 27-29, 2022, the first annual meeting of N3AS was held in Berkeley together with their international partners, RIKEN iTHEMS and CNRS Centre Pierre Binetruy. iTHEMS members are encouraged to use RBC as a base to interact with researchers in physics, mathematics, biology and related fields at Berkeley.
2022-06-09
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Ryosuke Iritani was interviewed by The Big Issue of Japan
Ryosuke Iritani (Research Scientist, iTHEMS) is interviewed by The Big Issue Japan, and the latest volume (vol 432) is just published on 1st June. The Big Issue is a magazine dedicated to supporting people in difficult circumstances and helping them achieve self-reliance. Each issue costs 450 yen, out of which 230 yen is the direct income of the street sales staff. The content is about mathematical biology and is accessible for anyone. We hope as many people as possible take it a read and support the people!
2022-06-06
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Common Laws of Evolution and Ecological Dynamics
The research team of Kyosuke Adachi (Special Postdoctoral Researcher, iTHEMS / Special Postdoctoral Researcher, Nonequilibrium Physics of Living Matter RIKEN Hakubi Research Team, RIKEN Center for Biosystems Dynamics Research (BDR)), Ryosuke Iritani (Research Scientist, iTHEMS) and Ryusuke Hamazaki (Senior Research Scientist, iTHEMS / RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR)) have proposed a broadly valid formula for theoretical models of evolutionary and ecological population dynamics using methods from information theory and statistical physics. The results of this research are expected to lead to a unified framework for understanding complex population dynamics in evolutionary and ecological systems over time. For more information, please see the related link.
2022-06-06
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Discovering Speed Limits for Macroscopic Transitions - A Unified Approach Based on the Equation of Continuity
Ryusuke Hamazaki (RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team / Senior Research Scientist, iTHEMS) has discovered a new inequality for the “speed limit," or transition rate, which is useful for physical processes that involve "macroscopic transitions". The research results are expected to have implications for nonequilibrium statistical mechanics, including the time scale of thermalization of quantum many-body systems. They are also expected to contribute to the fundamental understanding of quantum technology, e.g., the control of macroscopic quantum systems, which has become important in recent years. Please see related link for more details.
2022-05-09
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Clear Visualization of Lamb Waves from Tonga's Undersea Volcano Eruption -The Full Picture of the Waves Captured by the Himawari-8
Takemasa Miyoshi (Deputy Program Director, iTHEMS / Team Leader, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS)) and Shigenori Otsuka (Research Scientist, iTHEMS / Research Scientist, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS)) have developed an original method to clearly visualize "Lamb waves," a type of sound wave associated with Tonga's undersea volcanic eruption in January 2022, using images from the Himawari 8 meteorological satellite. Furthermore, we developed a method to automatically extract the Lamb waves from this image and clarified the relationship between the distribution of arrival times and ground pressure observations. The results of this research are expected to contribute to the scientific understanding and monitoring of atmospheric waves and associated tidal fluctuations caused by volcanic eruptions, and to the development of advanced simulations and future forecasting methods by integrating observation data with large-scale atmospheric and oceanographic calculations. Please see related links for more details.
2022-05-09
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RIKEN Research: Quantum computing and deep learning could help solve the mysteries of quantum gravity
RIKEN physicists have put quantum computing and deep learning through their paces and found that they are powerful tools for gleaning insights into new theories of quantum gravity [1]. They could thus help solve one of the most formidable challenges in modern physics—developing a theory of gravity that jives with quantum physics. When Einstein nutted out his theory of general relativity in 1915, his only tools were pen and paper. The same was true of the pioneers of quantum theory. But the next major breakthrough in theoretical physics could be made with help from emerging technologies such as quantum computers and machine learning, Enrico Rinaldi of RIKEN Theoretical Quantum Physics Laboratory thinks. “I believe these technologies are poised to transform the way we do theoretical physics,” he says. To read more, please visit the related link.
2022-04-25
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iTHEMS x academist online event was held on April 24, 2022
As the alternative for the lectures at RIKEN’s annual open house, iTHEMS held another online lecture event for the general public with the help of Academist Inc., on April 24th, 2022. This year, the lectures were Masaki Taniguchi, Hidetoshi Taya, Akira Harada, Yingying and Euki Yazaki, who all gave splendid public lectures accessible even to junior-high school students. Each lecturer also served as a commentator to another lecture, asking questions on behalf of the audience. During the lunch break, Program Director Hatsuda showed the offices of iTHEMS and around. The event was moderated by Ms. Michibayashi from Academist; Her facilitation with a wit kept the event lively. At one time during the event, more than two hundred audiences participated.
2022-04-25
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iTHEMS Starter Meeting for FY2022 on April 8, 2022
The iTHEMS Starter Meeting for FY 2021 was held over Zoom as past two years’ meeting to kick off its activity for FY 2022. Over seventy iTHEMS members, frequent visitors and colleagues from other institute got together and introduced each other.
2022-04-11
Videos
Skip this content to next content
Khovanov homology theory - an introduction to categorification by Dr. Taketo Sano on May 13, 2022
Fundamentals Fest, mini Pre-event on Science "Exploring and Bridging: The Potential of Basic Science"
In Search of Pc pentaquark - Simulate Hadron Interactions with FUGAKU
AAS Journal Author Series: Hirotaka Ito on 2021ApJ…918...59I
Will Useless Knowledge Change the Future? - What is the Black Hole Recorder?
RIKEN 2019 (in Japanese)
Comparison between conventional computers and quantum computers
A glimpse of enumerative geometry
Message-passing algorithms for graphical models
Canonical form of tensor networks in one and two dimensions
The basics of topological band theory
Building something from nothing: a mathematical framework for aperiodic/amorphous sets
Planetary lightning: Current State-of-the-art and outstanding questions
Collective Power of Science ~ from the High-Energy Atmospheric Physics to our New Exploration of the Universe ~
Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) is an international research program at RIKEN. It facilitates close collaborations among researchers from different disciplines in theoretical, mathematical and computational sciences. The ultimate goal of iTHEMS is to unravel the mystery of the Universe, matter, and life, as well as to solve key problems in modern society through interdisciplinary approaches.
Upcoming Events
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Seminar In Session
Gradient flow exact renormalization group 2
July 6 (Wed) at 13:30 - 17:00, 2022
Prof. Hiroshi Suzuki (Professor, Graduate School of Science, Kyushu University)
Wilson’s exact renormalization group (ERG), which tells how a system changes under the scale transformation, provides a fundamental framework to define quantum field theory even beyond the perturbation theory. It has however been known that it is difficult to preserve a manifest gauge symmetry in ERG because of the usage of the momentum cutoff in ERG. Here, we propose a possible modification of ERG, the gradient flow exact renormalization (GFERG), which preserves a manifest gauge symmetry being based on a gauge-covariant diffusion equation. I explain the basic idea and properties of GFERG. If time permits, I want to present a possible application of GFERG to the consideration of the axial anomaly.
Venue: via Zoom
Event Official Language: English
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Seminar Tomorrow
Virus vs. Bacteria: Art of the war in the microbial world
July 7 (Thu) at 16:00 - 17:00, 2022
Dr. Namiko Mitarai (Associate Professor, Niels Bohr Institute, University of Copenhagen, Denmark)
A virulent phage (virus that infects bacteria) infection to a host bacterial cell results in lysis of the cell, where possibly hundreds of phage particles are released after a latency time. The phage pressure is believed to be an important factor to shape the microbial communities and a driving force of their evolution, and yet we are far from having a full picture of their warfare. In this talk, I highlight a few factors that play significant roles in phage-bacteria interactions and their coexistence, such as the effect of herd immunity and the importance of the spatial structure in a few cells scale to the colony scale. *Her talk will be accessible to physicists, mathematicians, and also biologists.
Venue: via Zoom
Event Official Language: English
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ColloquiumThe 20th MACS Colloquium
July 8 (Fri) at 15:00 - 18:00, 2022
Dr. Akira Mori (Associate Professor, Division of Biological Sciences, Graduate School of Science, Kyoto University)
Dr. Namiko Mitarai (Associate Professor, Niels Bohr Institute, University of Copenhagen, Denmark)15:00-16:00 Talk by Dr. Akira Mori "Defense with prey toxins: A snake that has both venomous and poisonous glands" 16:15-17:15 Talk by Dr. Namiko Mitarai "Who "sleeps" and when? Bacterial growth and dormancy" 17:15-18:00 Discussion
Venue: via Zoom
Event Official Language: Japanese
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Seminar
Stem cells determine complexity of hematopoiesis and immunity: A key in maintenance of homeostasis and fighting disease
July 11 (Mon) at 10:00 - 11:30, 2022
Dr. Fumihiko Ishikawa (Team Leader, Laboratory for Human Disease Models, RIKEN Center for Integrative Medical Sciences (IMS))
The hematopoietic system, is a complex organ in which all cells, including white blood cells (also known as leukocytes), red blood cells and platelets originate from the hematopoietic stem cells. White blood cells/leukocytes are critical effectors of immunity. At baseline, we have about 5000-10000/microL circulating white blood cells/leukocytes, composed of more than ten distinct subsets. Among them, the most abundant (50-60%) is the neutrophil, which are capable of preventing bacterial and fungal infection. Others include T lymphocytes which attack tumors and virus-infected cells and B lymphocytes that produce immunoglobulins. Each of the leukocyte subsets have different roles in protecting us from diseases. Defects in white blood cell number or function expose us to risks of infections and tumors. Maintenance of normal homeostasis of these white blood cells is governed by expression levels of approximately 20,000 genes in hematopoietic stem cells. In this presentation, first, I will discuss current understanding of a hierarchical system of stem cells generating many different kinds of leukocytes. Second, I will talk about leukemia, a cancer of white blood cells, in which critical genes are hit by mutations, resulting in a loss or gain of function of those genes in stem cells. Third, I would like to discuss with the iTHEMS scientists potential approaches by which we can collaborate to understand the normal and diseased human blood/immune systems.
Venue: Hybrid Format (Common Room 246-248 and Zoom)
Event Official Language: English
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Seminar
Adiabatic pumps in quantum spin systems
July 12 (Tue) at 16:00 - 17:15, 2022
Dr. Ken Shiozaki (Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
The Thouless pump is a one-parameter cycle of 1-dimensional gapped quantum systems with U(1) symmetry, which is classified by integers. In this talk, I introduce a generalization of the Thouless pump to quantum spin systems in any dimension with any finite group onsite symmetry. I show a simple model with Z_2 onsite symmetry, and how it is nontrivial via boundary degrees of freedom. Using the framework of the injective matrix product state, one can construct the topological invariant in a way similar to the Berry phase. If time allows, I will briefly introduce a group cohomology model by Roy and Harper for generic space dimensions and discuss its properties.
Venue: via Zoom
Event Official Language: English
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SeminarSpeed limits for macroscopic transitions
July 13 (Wed) at 13:30 - 15:00, 2022
Dr. Ryusuke Hamazaki (RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR))
Speed of state transitions in macroscopic systems is a crucial concept for foundations of nonequilibrium statistical mechanics as well as various applications in quantum technology represented by optimal quantum control. While extensive studies have made efforts to obtain rigorous constraints on dynamical processes since Mandelstam and Tamm, speed limits that provide tight bounds for macroscopic transitions have remained elusive. Here, by employing the local conservation law of probability, the fundamental principle in physics, we develop a general framework for deriving qualitatively tighter speed limits for macroscopic systems than many conventional ones. We show for the first time that the speed of the expectation value of an observable defined on an arbitrary graph, which can describe general many-body systems, is bounded by the “gradient” of the observable, in contrast with conventional speed limits depending on the entire range of the observable. This framework enables us to derive novel quantum speed limits for macroscopic unitary dynamics. Unlike previous bounds, the speed limit decreases when the expectation value of the transition Hamiltonian increases; this intuitively describes a new trade-off relation between time and the quantum phase difference. Our bound is dependent on instantaneous quantum states and thus can achieve the equality condition, which is conceptually distinct from the Lieb-Robinson bound. We also find that, beyond expectation values of macroscopic observables, the speed of macroscopic quantum coherence can be bounded from above by our general approach. The newly obtained bounds are verified in transport phenomena in particle systems and nonequilibrium dynamics in many-body spin systems. We also demonstrate that our strategy can be applied for finding new speed limits for macroscopic transitions in stochastic systems, including quantum ones, where the bounds are expressed by the entropy production rate. Our work elucidates novel speed limits on the basis of local conservation law, providing fundamental limits to various types of nonequilibrium quantum macroscopic phenomena.
Venue: Hybrid Format (Common Room 246-248 and Zoom) (Main Venue) / via Zoom
Event Official Language: English
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SeminarSeiberg-Witten Floer homotopy
July 15 (Fri) at 14:00 - 16:30, 2022
Dr. Hokuto Konno (Assistant Professor, Graduate School of Mathematical Sciences, The University of Tokyo)
I will survey a mathematical object called the Seiberg-Witten Floer homotopy type introduced by Manolescu. This is a machinery that extracts interesting aspects of 3- and 4-dimensional manifolds through the Seiberg-Witten equations. This framework assigns a 3-manifold to a "space" (more precisely, the stable homotopy type of a space), and this space contains rich information that is strong enough to recover the monopole Floer homology of the 3-manifold, which is known already as a strong invariant. I shall sketch how this theory is constructed along Manolescu's original work, and introduce major applications. If time permits, I will also explain recent developments of Seiberg-Witten Floer homotopy theory. If you are not familiar with the mathematical formulation of TQFT and categorification, I recommended you to watch Dr. Sano's recent talk in advance (see related links).
Venue: Hybrid Format (Common Room 246-248 and Zoom)
Event Official Language: English
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Seminar
Superconducting-like heat current: Effective cancellation of current-dissipation trade-off by quantum coherence
July 25 (Mon) at 13:30 - 15:00, 2022
Dr. Tajima Hiroyasu (Assistant Professor, Graduate School of Informatics and Engineering, The University of Electro-Communications)
Recent developments in statistical mechanics have revealed a tradeoff between heat current and dissipation [1,2]. In various situations, this current-dissipation tradeoff represents a relationship between thermal energy flow and entropy increase, similar to Joule’s law W=RI^2. On the other hand, the coherence effect on the current-dissipation tradeoff has not been thoroughly analyzed. Here, we systematically analyze how coherence affects the current-dissipation tradeoff [3]. The results can be summarized in the following three rules:
Venue: via Zoom
Event Official Language: English
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ColloquiumFrom the Black Hole Conundrum to the Structure of Quantum Gravity
July 26 (Tue) at 15:30 - 17:00, 2022
Prof. Yasunori Nomura (Director, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA)
Having a complete quantum theory of gravity has long been a major goal of theoretical physics. This is because a naive merger of quantum mechanics and general relativity — though it works in certain limited regimes — suffers from major theoretical problems. A particularly acute one arises when one considers the quantum mechanics of black holes: two fundamental principles of modern physics — the conservation of probability in quantum mechanics and the equivalence principle of general relativity — seem to be incompatible with each other. I will explain how recent theoretical progress begins to address this problem and portray the emerging picture of how spacetime and gravity behave at the level of full quantum gravity.
Venue: 2F Large Meeting Room, RIBF Building, RIKEN Wako Campus / via Zoom
Event Official Language: English
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Workshop
iTHEMS Science Outreach Workshop 2022
July 29 (Fri) - 31 (Sun), 2022
This year’s meeting on “Outreach of RIKEN iTHEMS 2022@Kobe&Zoom” will be held from FRI July 29 to SUN July 31, as a face-to-face meeting as much as possible at iTHEMS SUURI-COOL Kobe using ZOOM for the necessary part as well. This is a meeting where members of iTHEMS and science journalists, science writers, etc meet together. iTHEMS researchers explain their research to journalists etc. and science journalists and writers talk about their experiences.
Venue: SUURI-COOL (Kobe) / via Zoom
Event Official Language: Japanese
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Workshop
DM3 - Deep insights and Multiple strategies for Deciphering the Mystery of Dark Matter
September 15 (Thu) - 17 (Sat), 2022
Venue: SUURI-COOL (Kobe) / via Zoom
Event Official Language: English
Opportunities
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Seeking a Coordinator (W22037)
Deadline: August 5, 2022
Coordinator one position. The applicant should have experience in managing project(s) involving more than one research organization, as well as experience in acquiring and managing research funding.
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Seeking a Research Scientist or Senior Research Scientist (W21319) *theoretical and mathematical biology or biophysics
Deadline: Open until filled
Research Scientists or Senior Research Scientists a few positions. iTHEMS is seeking a research scientist or senior research scientist in theoretical and mathematical biology or biophysics. The successful applicant is expected not only to pursue top-level research in mathematical science but also to lead interdisciplinary collaborations among different fields such as mathematics, physics, chemistry, biology, information sciences, computational sciences, and social sciences, under the concept of iTHEMS.
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Seeking a Research Scientist or Senior Research Scientist (W21320) *mathematical sciences including pure mathematics
Deadline: Open until filled
Research Scientists or Senior Research Scientists a few positions. iTHEMS is seeking a research scientist or senior research scientist in mathematical sciences including pure mathematics, applied mathematics and information sciences. Successful applicant is expected not only to pursue top-level research in mathematical science but also to lead interdisciplinary collaborations among different fields such as mathematics, physics, chemistry, biology, information sciences, computational sciences, and social sciences, under the concept of iTHEMS.
Latest News
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2022-07-06
Seminar Report
iTHEMS Biology Seminar by Mr. Keiichi Morita on June 23, 2022
I talk about how evolution of sexual traits such as ornaments of guppies can affect coexistence of two closely related species. First, I introduce "reproductive interference," sexual interaction driving evolution of sexual traits. Second, I show how to formulate population dynamics of two closely related species with reproductive interference. Next, I introduce mathematical modeling of quantitative genetics in order to formulate trait evolution. Finally, I show results of analysis and simulation by combining population dynamics and evolution (i.e., eco-evolutionary feedbacks). In future works, I should the effect of costs of evolution or the other species. Thank you for your listening and giving me comments! Reported by Keiichi Morita
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2022-07-05
Seminar Report
Quantum Matter Seminar by Dr. Thore Posske on June 30, 2022
Dr. Thore Posske from the University of Hamburg gave an online seminar about controlling topological quantum effect in spin systems by manipulating the boundary. He first introduced the idea that topology can connect multiple subfields in physics and then showed how a 1D spin chain can be controlled to form a helix or the ground state by manipulating the evolution of the two chain ends. Since the different quantum states can be controlled by the boundary, this is a potential platform for quantum computing to generate distinct quantum states. Furthermore, the boundary idea was extended to 2D spin systems. By properly changing the spins on the edges, a skyrmion can emerge. In the end, the speaker talked about an experimental approach to distinguishing the topological phases in systems with periodic boundary conditions by multi-pulse spectroscopy, and applied these ideas to 1D topological superconductors. Reported by Thore Posske (University of Hamburg) and Ching-Kai Chiu
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2022-07-04
Seminar Report
ABBL-iTHEMS Joint Astro Seminar by Mr. Tomoki Matsuoka on July 1, 2022
Mr. Tomoki Matsuoka gave an excellent talk on the long-term evolution of a supernova remnant hosting a double neutron star binary. He presented that stellar mass loss is one of the crucial elements determining the fate of core-collapse supernovae progenitors (SNe). Since the material released from the progenitor will be distributed as circumstellar medium (CSM), it can also influence the subsequent evolution of the SN or supernova remnant (SNR). Despite its importance, mass loss histories predicted by stellar evolution models have not been incorporated with modeling for SNRs. As a first step, he investigated the dynamical evolution of an ultra-stripped supernova remnant (USSNR), which originated from a core-collapse SN explosion proposed to be a candidate formation site of a double neutron star binary. By accounting for the mass-loss history of the progenitor binary using a model developed by a previous study, he constructed the large-scale structure of the CSM up to a radius ∼100 pc. Then, he simulated the explosion and subsequent evolution of a USSN surrounded by such a CSM environment. He found that the CSM encompasses a vast region characterized by a hot plasma with a temperature ∼10^8 K located around the termination shock of the wind from the progenitor binary (∼10 pc), and the USSNR blast wave is drastically weakened while penetrating through this hot plasma. Radio continuum emission from a young USSNR is sufficiently bright to be detectable if it inhabits our galaxy but faint compared to the observed Galactic SNRs. In this seminar, he talked about the background of the connection between the models for stellar evolution and SNRs, the details of his methods, and future prospects very well. Reported by Shigehiro Nagataki