Volume 87

iTHEMS Weekly News Letter

Hot Topic

Tomoki Ozawa thumbnail

Farewell note from Dr. Tomoki Ozawa

2020-01-30

Hello. My name is Tomoki Ozawa. I am a senior research scientist at RIKEN iTHEMS. As of February, I am leaving iTHEMS and moving to Advanced Institute for Materials Science (AIMR) in Tohoku University, Sendai, to start my own group as an associate professor.

I joined iTHEMS on April 2018; I cannot believe that it has already been almost two years. Time really flies like an arrow. Before joining iTHEMS, my research career has been developed abroad (US, Italy, Belgium), and although I am a native of Japan, iTHEMS is the first Japanese affiliation I obtained as a researcher. Before coming back to Japan, I had always been worried if I could be accepted to the Japanese academic community. After joining iTHEMS, I learned that my worries were needless. I was surprised by the welcoming atmosphere of iTHEMS, and even though I was the only condensed matter physicist in iTHEMS, I could easily find somebody to discuss in the iTHEMS coffee room. What helped me even more to place myself in Japan were the various satellite offices of iTHEMS in (and also outside) Japan. These satellite offices made it easy for me to visit and know what is going on in various other places in Japan. After spending almost two years in iTHEMS, although I am still constantly surprised by cultural differences between Japan and other places I have been, I feel that I have comfortably become a part of the academic community in Japan.

In terms of research, what was great being in iTHEMS was that I could do whatever research I wanted to do, without any pressure on the selection of topic or to report what I am doing to my boss. I really appreciated the academic freedom here. I am also starting to build collaborations in Japan. The new collaborations I am building are quite interdisciplinary (including atomic physics, photonics, and even biophysics), thanks to the wide scope of interests of people in iTHEMS.

It has been a real pleasure to spend time in the beginning period of iTHEMS, and I am sure that iTHEMS will flourish even more in the coming years. AIMR has a satellite office of iTHEMS, and I expect to maintain active interactions with iTHEMS after I move to AIMR. I will also most likely come to iTHEMS offices (perhaps the coffee room in Wako) from time to time, and I am looking forward to seeing the successful development of iTHEMS in the future.

Hot Topic

Seminar Report

Math seminar by Dr. Shu Nakamura

2020-01-24

The iTHEMS Math seminar was held on 23 January, inviting Shu Nakamura from Gakushuin university. The title of the talk was “Semiclassical methods in mathematical quantum mechanics”. The topic was semiclassical analysis and scattering theory of Schrödinger operators.
In the first part, the speaker gave a introductory talk on the microlocal analysis and semiclassical analysis of Schrödinger operators. He started his talk by introducing a canonical quantization. Then he explained how canonical quantization is understood in the framework of semiclassical and microlocal analysis. Moreover he explained some recent results on this research field.
In the second part, the speaker explained his recent results on scattering matrix of Schrodinger operators with long range potentials. At the beginning, he introduced the definition of scattering matrix and some known results. Then he stated his main result on the representation of scattering matrix. As an application, he gave some examples of long range potentials for which he proved several spectral properties of scattering matrix.

Upcoming Events

Seminar

ABBL-iTHEMS Joint Astro Seminar

ABBL/iTHEMS seminar - talk on ultra-high energy cosmic rays

January 31 (Fri) at 14:00 - 15:00, 2020

Eiji Kido (Astrophysical Big Bang Laboratory, RIKEN Cluster for Pioneering Research (CPR))

Venue: Seminar Room #132, 1F Main Research Building, RIKEN

Event Official Language: English

Seminar

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iTHEMS Math Seminar

Solved and open problems regarding the neighborhood grid data structure

February 7 (Fri) at 16:00 - 18:10, 2020

Martin Skrodzki (Visiting Scientist, iTHEMS / Fellow, German Academic Scholarship Foundation, Germany)

February 7 at 16:00-17:00 17:10-18:10, 2020

In 2009, Joselli et al. introduced the neighborhood grid data structure for fast computation of neighborhood estimates for point clouds in arbitrary dimensions. Even though the data structure has been used in several applications and was shown to be practically relevant, it is theoretically not yet well understood even in the two-dimensional case. The purpose of this talk is to present the data structure, give a time-optimal building algorithm, and motivate several associated questions from enumerative combinatorics as well as low-dimensional (probabilistic) geometry. In case of questions that have been solved in the past, corresponding proofs will be provided. For the open question, the talk will list them as an outlook to possible future collaboration.

Venue: Seminar Room #160, 1F Main Research Building, RIKEN

Event Official Language: English

Colloquium

The 11st MACS Colloquium thumbnail

MACS ColloquiumSupported by iTHEMSSUURI-COOL (Kyoto)

The 11st MACS Colloquium

February 19 (Wed) at 15:00 - 17:30, 2020

Hiroyuki Hata (Professor, Graduate School of Science, Kyoto University)

15:00- Teatime
15:15- Talk by Prof. Hiroyuki Hata
16:40- MACS Report Meeting FY2019

The 11th MACS colloquium is 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

Seminar

iTHEMS Math Seminar

Index of the Wilson-Dirac operator revisited: a discrete version of Dirac operator on a finite lattice

February 25 (Tue) at 16:00 - 18:10, 2020

Mikio Furuta (Professor, The University of Tokyo)

The Wilson-Dirac operator is a discrete version of Dirac operator defined on regular lattices. When the discrete version is a fine approximation of the Dirac operator on a Z/2-graded Clifford module on a torus, it is known that (1) an integer-valued index is defined for the Wilson-Dirac operator, and (2) the index is equal to the Atiyah-Singer index of the Dirac operator on the torus.
These have been well established up to around 2000. The strategy of all the previous works is to make use of the discrete version of the heat kernel for Neuberger's overlap Dirac operator. Therefore the strategy cannot be generalized to mod 2 index nor family version of index.
In this talk I would like to explain a new approach to the index of Wilson-Dirac operator which can be immediately generalized to these various cases.
Joint work with H. Fukaya, S. Matsuo, T. Onogi, S. Yamaguchi and M. Yamashita.

Venue: Seminar Room #160, 1F Main Research Building, RIKEN

Event Official Language: English

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