Introduction to magnitude of metric spaces

July 22 (Mon) at 13:00 - 15:00, 2019

Genki Ouchi (Special Postdoctoral Researcher, iTHEMS)

Leinster introduced the notion of magnitude of a metric space. It is a real number measuring the effective number of points in a metric space. In this talk, I will review generalizations of metric spaces (e.g. asymmetric metric spaces). After that, I would like to talk about the definition, examples and fundamental properties of magnitude.

Venue: Seminar Room #160

Event Official Language: English

Workshop to bring together experts on High Energy Astrophysics from Japan and Israel

July 18 (Thu) - 23 (Tue), 2019

This workshop is co-organized by iTHEMS. 1st week (July 18-19th) Place: Okochi Hall, RIKEN, Wako, Saitama, Japan 2nd week (July 22-23th) Place: Integrated Innovation Building (IIB), RIKEN, Kobe, Hyogo, Japan

Venue: Okochi Hall / Integrated Innovation Building (IIB)

Event Official Language: English

The 9th MACS Colloquium

July 12 (Fri) at 16:15 - 18:50, 2019

Makoto Fujita (Professor, Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo)
Kazutoshi Mori (Professor, Department of Biophysics, Division of Biological Sciences, Graduate School of Science, Kyoto University)

16:15- Teatime 16:30- Talk by Prof. Makoto Fujita 17:50- Talk by Prof. Kazutoshi Mori The 9th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good confectionery at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Event Official Language: Japanese

Introduction to Schroedinger Operators

July 12 (Fri) at 16:00 - 18:10, 2019

Keita Mikami (Research Scientist, iTHEMS)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half. Abstract: In this seminar, I will talk about mathematical study of Schroedinger operators (or Schroedinger equation). Part 1: I will talk about what mathematicians do to find a solution to Schroedinger equation. The goal of the first part is to be able to check the existence of solutions of Schroedinger equations in terms of decay/growth rate of potentials. Part 2: I will talk about what can we say about solutions to Schroedinger equation constructed in the first part. Especially, the relationship to the corresponding classical mechanic is introduced.

Venue: Seminar Room #160

Event Official Language: English

Large scale dynamics of integrable systems

July 12 (Fri) at 16:00 - 17:00, 2019

Takato Yoshimura (King's college London, UK)

Hydrodynamics has been a universal tool to study the large scale (long-wavelength) dynamics of interacting many-body systems. It had not been, however, applied to integrable systems until 2016 when two papers, one of which is ours [Physical Review X 6 (4), 041065, (2016)], provided a first legitimate hydrodynamic theory of integrable systems that incorporates the anomalous number of conserved quantities in those systems. The key idea of the theory rests upon the use of thermodynamic Bethe ansatz that allows us to express the essential ingredients in hydrodynamics, densities and currents average of conserved charges, in terms of the quasi-particle basis. In this talk I will review this new hydrodynamic theory, coined generalized hydrodynamics (GHD). I will first introduce the basics of GHD, highlighting the difference with the conventional hydrodynamics (i.e. hydrodynamics for non-integrable systems). I will then present some recent developments in the theory, such as the exact computation of the Drude weight and hydrodynamic correlation functions.

Venue: Building 14 #213, Yagami campus, Keio University

Event Official Language: English

SOKENDAI-iTHEMS Joint Workshop "Genetics meets Mathematics"

July 7 (Sun) - 8 (Mon), 2019

Jeffrey Fawcett (Senior Research Scientist, iTHEMS)

7月7,8日に総研大葉山キャンパス近くの研修施設レクトーレ葉山にて遺伝・進化の研究者と数学・物理の研究者の交流を深めることを目的としたインフォーマルなワークショップを開催します。 生物の知識が全くない（主に数学・物理の）研究者を対象とした、生命の分子レベルでの多様性を説明しうる集団遺伝や分子進化の理論などに関するレクチャーを行います。また、今後の相互作用の可能性がありそうなテーマに取り組む数学・物理の研究者にも講演していただきます。 参加費・宿泊費は無料（懇親会費を頂く場合があります）で、前日の7/6と7/7に会場の宿泊施設に泊まることが可能です。プログラムの詳細は今後変更する場合があります。 登録締切：6/24 （宿泊者数に限りがあるため早めに締め切る場合があります） Organizers: Jeffrey Fawcett (RIKEN iTHEMS), Tetsuo Hatsuda (RIKEN iTHEMS), Shohei Takuno (SOKENDAI), Hideki Innan (SOKENDAI)

Venue: LecTore Hayama

Event Official Language: Japanese

RIKEN-OIST mini Workshop 2019 "Mathematical Condensed Matter Physics"

July 5 (Fri) - 6 (Sat), 2019

Topics: Boson-Fermion duality, Operator product expansion, Random matrix Lecturers: Takuya Furusawa (TIT/RIKEN) Yuta Sekino (RIKEN) Shinobu Hikami (OIST) Organizers: Masahiro Nozaki (RIKEN) Chair person Masaru Hongo (Keio Univ./RIKEN) Kanato Goto (RIKEN) Hidehiko Shimada (OIST)

Venue: Okinawa Institute of Science and Technology Graduate University (OIST)

Event Official Language: English

1-day Workshop on Quantum Gravity

July 4 (Thu) at 9:30 - 18:00, 2019

In order to construct a quantum theory of gravity, it is currently required to study freely from various viewpoints. In this small workshop, we will discuss various different topics such as field theory, string theory, quantum black hole, quantum universe and so on, and will consider future directions to quantum gravity casually but deeply. Let's enjoy exciting discussions!

Venue: Seminar Room #132

Event Official Language: English

Spacetime Geometry of Black Holes, Wormholes, and Time Machines

July 2 (Tue) at 15:30 - 17:00, 2019

Pei-Ming Ho (Distinguished Professor, Department of Physics, National Taiwan University, Taiwan)

Since the advent of General Relativity, people have found many solutions with interesting spacetime geometries. Most notably, the black holes have attracted a lot of attention for their roles in generating gravitational waves, and for inducing the information loss paradox. In this talk, we consider black holes amongst other geometric structures and investigate the subtlety involved in the quantum effect such as Hawking radiation. In this context, we mention wormholes and time machines, and explain how they are conceptually related to the geometry under the horizon of a black hole. There will also be comments on my recent research result about how quantum effect must be large for observers sitting on top of the black hole horizon.

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Broadcast:R511, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: English

ABBL/iTHEMS/r-EMU Joint Seminar: Towards systematic and consistent nuclear data inputs for astrophysical r-process with Bayesian approaches

June 28 (Fri) at 14:00 - 15:00, 2019

Haozhao Liang (Senior Research Scientist, Quantum Hadron Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science (RNC))

This is his 2nd seminar talk for non-experts of nuclear physics, following the 1st one on 18th Jan. 2019. Abstract: In this interdisciplinary talk, I will start with some basic concepts as well as some frontiers of nuclear physics, and then introduce the roles of nuclear data inputs for the study of astrophysical rapid neutron-capture process (r-process), which is responsible for the creation of approximately half the abundances of the atomic nuclei heavier than iron. Recent progress in nuclear physics focuses on improving the accuracy of crucial nuclear inputs, such as nuclear masses, beta-decay half-lives. Nevertheless, in most of the studies these inputs are investigated individually. One of our ongoing attempts is to organize the crucial nuclear inputs in a systematic and consistent way, together with Bayesian and/or machine learning approaches, which are able to provide not only the theoretical results but also the corresponding uncertainties.

Venue: 224-226, Main Research Building

Event Official Language: English

Asymmetric metric and coarse geometry

June 20 (Thu) at 16:00 - 18:10, 2019

Hiroki Kodama (Visiting Scientist, iTHEMS / Assistant Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half. Abstract: For most of mathematicians, metric is symmetric. However, we can define asymmetric metric without any difficulty. "Coarse" is a notion to describe some large scale viewpoint. For example, the set of real numbers is coarse equivalent to the set of integers (with respect to standard metric). I will discuss asymmetric metric space in "coarse" sense. Part 1: I will define metric space and asymmetric metric space. I will also explain a notion of coarse equivalence. Part 2: I will discuss what kind of asymmetric metric space is not coarse equivalent to (symmetric) metric space. I also would like to give other generalizations of metric.

Venue: Seminar Room #160

Event Official Language: English

Using combined Particles-in-MHD-Cells to model particle acceleration in astrophysical shocks

June 17 (Mon) at 14:00 - 15:00, 2019

Allard Jan van Marle (Research Professor, Ulsan National Institute of Science and Technology, Republic of Korea)

Astrophysical shocks can accelerate charged particles through diffusive shock acceleration. This process involves repeated shock crossings where the particle gains energy from collisions with the electromagnetic field. Eventually, these particles will reach relativistic speeds and can be observed as cosmic rays. In order to simulate this process, we need a method that can handle both the large-scale structure of astrophysical shocks, as well as the behaviour of individual particles. We achieve this by combining the classical magnetohydrodynamics (MHD) and particle-in-cell (PIC) methods. This allows us to describe the thermal plasma of the shock through MHD, while simultaneously using PIC to follow the movement of non-thermal particles as they are accelerated. Our results show a complicated interaction that destabilizes the shock, reducing the efficiency with which particles can be accelerated.

Venue: Seminar Room #132

Event Official Language: English

g-RIPS Sendai 2019

June 17 (Mon) - August 9 (Fri), 2019

GRIPS (Graduate-level Research in Industrial Projects for Students)-Sendai program was held last summer (June 18 - Aug. 10, 2018) with the support of iTHEMS as well as other institutions and companies. Two industrial projects were launched under the suggestion of TOYOTA and NEC, and two teams composed of US and Japanese students have worked intensively to find solutions of these problems. See for the details of the GRIPS program and the summary of activities at GRIPS-Sendai 2018. This year, GRIPS-Sendai program will be held from June 17 through Aug. 9, 2019 with a larger scale under the support of iTHEMS. Stay tuned for further information.

Venue: 4F Research Space, AIMR Main Building

Event Official Language: English

Quantum physics and science with open-source software: QuTiP, the Quantum Toolbox in Python

June 13 (Thu) at 10:00 - 11:30, 2019

Nathan Shammah (Postdoctoral Researcher, Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research (CPR))

I will address the rise of open source software based on the Python language ecosystem in quantum physics research, in particular with relevance to quantum technology and quantum computing. I will introduce the Quantum Toolbox in Python, QuTiP, a very popular software in the quantum tech community, whose core development has revolved around Prof. F. Nori’s group at RIKEN since 2011. QuTiP is open-source software for simulating the dynamics of closed and open quantum systems, and is used for quantum information science and cavity quantum electrodynamics studies. The QuTiP ecosystem has grown considerably in the past years, with many quantum tech libraries using its functionalities, similarly to what has happened for AstroPy in the astrophysics community. Following the seminar, an interactive session will illustrate some features of this software package library. I will also show, drawing from recent research examples, how everyone can build its own library. Only a laptop with wifi working is required to join the hands-on session.

Venue: Nishina Hall

Event Official Language: English

Quantum Mechanics of an Evaporating Black Hole

June 6 (Thu) at 15:30 - 17:00, 2019

Yasunori Nomura (Director, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA)

Venue: Seminar Room #160

Event Official Language: English

ABBL-iTHEMS Joint Seminars (Following r-EMU seminar 13:30-15:00)

May 31 (Fri) at 15:15 - 17:35, 2019

15:15-15:35 Hiroyuki Sagawa (ICRR, U.Tokyo) “Recent TA Results and the extension status for the study of the highest-energy cosmic rays” 15:35-16:30 Igor Tkachev (Russian Academy of Sciences) “Axion stars: from birth to death” 16:30-16:40 Break 16:40-17:35 Peter Tinyakov (U. Libre de Bruxelles) “Solar mass black holes and dark matter"

Venue: #435-437, Main Research Building

Event Official Language: English

iTHEMS Science Outreach Workshop 2019

May 31 (Fri) - June 3 (Mon), 2019

This is a workshop in which researchers in natural and mathematical sciences and the science journalists get together and discuss outreach activities. iTHEMS started to support this annual workshop as well as the journalist in residence program from last year to establish better science communication. Contact: Takashi Tsuboi (iTHEMS Deputy Director)

Venue: Tambara Institute of Mathematical Sciences, The University of Tokyo

Event Official Language: Japanese

Certain invariants as dimension

May 24 (Fri) at 16:00 - 18:10, 2019

Genki Ouchi (Special Postdoctoral Researcher, iTHEMS)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half. Abstract: In this talk, I would like to talk about certain invariants that look like dimension. This talk has independent two parts. In part 1, I will talk about finite metric spaces. In 2013, Leinster introduced the notion of magnitude of finite metric spaces. It measures effective number of points in finite metric spaces. Considering magnitude and scale transformation, Leinster and Willerton defined dimension of finite metric space with scale. I will explain the definition of magnitude of finite metric spaces and see examples. In part 2, I will talk about derived categories of smooth projective varieties or finite dimensional algebras. In 2014, Dimitrov, Heiden, Katzarkov and Kontsevich introduced the notion of entropy of endofunctors of derived categories. It measures complexity of endofunctors under iteration. Serre functor is an autoequivalence of derived category, that describes Serre duality. Entropy of Serre functor looks like dimension of derived categories. I will talk about known results for entropy of Serre functors and some related topics.

Venue: Seminar Room #160

Event Official Language: English

First M87 Event Horizon Telescope Results: The Shadow of the Supermassive Black Hole

May 24 (Fri) at 14:00 - 15:00, 2019

Yosuke Mizuno (Frankfurt University, Germany)

The Event Horizon Telescope (EHT) has mapped the central compact radio source of the elliptical galaxy M87 at 1.3 mm with unprecedented angular resolution. These images show a prominent ring with a diameter of ~40 micro-arcsecond, consistent with the size and shape of the lensed photon orbit encircling the “shadow” of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. Here we consider the physical implications of the asymmetric ring seen in the 2017 EHT data. To this end, we construct a large library of models based on general relativistic magnetohydrodynamic simulations and synthetic images produced by general relativistic ray tracing. We compare the observed visibilities with this library and confirm that the asymmetric ring is consistent with earlier predictions of strong gravitational lensing of synchrotron emission from a hot plasma orbiting near the black hole event horizon. Overall, the observed image is consistent with expectations for the shadow of a spinning Kerr black hole as predicted by general relativity. If the black hole spin and M87’s large scale jet are aligned, then the black hole spin vector is pointed away from Earth. Models in our library of non-spinning black holes are inconsistent with the observations as they do not produce sufficiently powerful jets. We also briefly discuss the possibility of the alternatives to a black hole for the central compact object.

Venue: #435-437, Main Research Building

Event Official Language: English