iTHEMS Weekly News Letter

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Season's Greetings from Dr. Tetsuo Hatsuda, iTHEMS Director


Season's Greetings and Best Wishes for the New Year

Thank you very much for sharing the joys of excellent science as well as your patience under COVID-19 during 2020.

We wish you a good holiday season and a safe new year 2021 with happiness, prosperity, and novel scientific perspectives.

Tetsuo Hatsuda, iTHEMS Director

Seminar Report

Math Seminar by Dr. Hideki Inoue on December 7, 2020


On December 7, there was a math seminar by Dr. Hideki Inoue. His talk aims to introduce Levinson's Theorem and its recent progress.

In the first part, he gave a brief survey talk on Levinson's theorem and its formulation. He then explained that Levinson's theorem, which can be proved analytically. He then introduced abstract scattering theory and operator algebras and how they applied to Levinson's theorem study.

In the second part, he explained his recent results on Levinson's theorem. He showed a straightforward representation formula of the wave operator, a significant research target in the scattering theory. With this formula, he proved that one could prove Levinson's theorem by abstract theory. He also explained similar results on discrete operators.

Seminar Report

Information Theory SG by Dr. Koichiro Yoshino on December 16, 2020


As the first seminar speaker of the Information Theory study group, we invited Koichiro Yoshino (Teamleader of Robotics Project, RIKEN) to give a talk on natural language processing. First, he explained the statistical language model's basis, e.g. language model, distributed representations, etc, and then discussed his own works: 1) attribute transfer in word embedding space, 2) modeling sentence structure. Natural language processing is one of the good applicants of information theory, and we enjoyed his clear talk and discussions.

Akinori Tanaka (iTHEMS/AIP)

Seminar Report

Information Theory SG by Dr. Ryusuke Hamazaki on December 16, 2020


In the journal club of Information Theory Study Group held on December 16th, Dr. Ryusuke Hamazaki (CPR/iTHEMS) gave us a talk about recent proposals of a quantum version of the Wasserstein distance. He first reviewed the commonly used quantities expressing the distance between probability distributions, i.e., the total variation distance and the relative entropy. After pointing out certain problems with these quantities, he introduced the classical Wasserstein distance of order 1 as a better definition of the distance and explained its representative properties like transportation inequality and tensorization property. Next, he introduced a quantum counterpart of the Wasserstein distance, which can apply to spin-1/2 quantum systems. In contrast to the total variation distance, the quantum Wasserstein distance has interesting properties like the invariance under permutation or local unitary transformation. Lastly, he explained an application of the quantum version of transportation inequality to the eigenvalue distribution. Reflecting the interdisciplinary subject of the talk, there were several questions and comments from both mathematical and physical viewpoints. We are grateful to Ryusuke for the great talk!

Kyosuke Adachi (BDR/iTHEMS)

Quantum Wasserstein distance of order 1 image

Seminar Report

Biology Seminar by Dr. Yuri Kominami on November 27, 2020


In iTHEMS Biology Seminar on November 27th, Dr. Yuri Kominami from University of Tokyo gave us a talk about her experimental study on population dynamics of rotifer. It is often difficult to understand population dynamics of animals because the population is reflected by complex environmental conditions. In her study, by using rotifer as a model organism, she has succeeded in measuring the laboratory population size, the birth rate, and the life span in a controlled condition. In this seminar, she showed some of nontrivial results of her experiment. Her discoveries were very exciting for theoretical biologists, and we enjoyed active discussion. Thank you so much, Kominami-san!
-Shingo Gibo

Upcoming Event


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iTHEMS Biology Seminar

Mathematical model-based quantitative data analysis for COVID-19

December 22 at 10:00 - 11:00, 2020

Prof. Shingo Iwami (Associate Professor, Mathematical Biology Laboratory, Department of Biology, Faculty of Science, Kyushu University)

The recent spread of corona threatens the health of people around the world. We urgently need strategies to reduce COVID-19 spread and to enhance antiviral drug development for individual patients. Mathematics could contribute to control of COVID-19 pandemic by informing decisions about pandemic planning, resource allocation, and implementation of social distancing measures and other interventions. My group is conducting interdisciplinary research to elucidate "Quantitative Population Dynamics" with original mathematical theory and computational simulation, which are both our CORE approach. Our mathematical model-based approach has quantitatively improved a current gold-standard approach essentially relying on the statistical analysis of "snapshot data" during dynamic interaction processes in virus infection. In my talk, I would like to discuss how our approach improves our current understanding of COVID-19 research, and help an establishment of a "standard antiviral treatment" for COVID-19 as well.

Venue: via Zoom

Event Official Language: English

Paper of the Week

Week 3 of December


Title: Phase transitions in the frustrated Ising ladder with stoquastic and non-stoquastic catalysts
Author: Kabuki Takada, Shigetoshi Sota, Seiji Yunoki, Bibek Pokharel, Hidetoshi Nishimori, Daniel A. Lidar

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