コーヒーミーティング過去ログ

2021-06-18

Phase transtion' in Kahler geometry

井上 瑛二 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員)

I am a new member of RIKEN iTHEMS and working on Kahler geometry in mathematics. As I cannot overview my study in this short time, I would like to explain a strange phenomenon now I am facing in Kahler geometry with a specific example. It is reminiscent of `phase transition' or `spontaneous symmetry breaking'. I hope it makes a chance of discussion with researchers in other areas.

2021-06-11

The death of a star: the theory of the supernova explosion

原田 了 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員)

At the end of the stellar evolution, the star explodes as bright as a galaxy and leaves a neutron star. This explosion is known as the supernova. Understanding the supernova explosion mechanism is crucial because it plays a vital role in the stellar and cosmic matter evolutions. The explosion mechanism includes a variety of physical processes, and hence it is a challenging problem. In this coffee talk, I would like to introduce the basic features of supernovae and the current understanding of the explosion mechanism.

2021-06-04

Canonical form of tensor networks in one and two dimensions

ヤンタオ・ウー (理化学研究所 数理創造プログラム (iTHEMS) 特別研究員)

I will be a new member of RIKEN iTHEMS and work on computational study in condensed matter physics. In this short coffee meeting, I would like to discuss the basics of tensor networks. I will be pedagogical and not assume knowledge of quantum mechanics. I will assume basic linear algebra at the level of singular value decomposition. I will introduce the graphical notation of a tensor network, and the notion of a canonical form in one dimension. If time permits, I will also discuss the canonical form in two dimensions.

2021-05-28

The basics of topological band theory

ツォン ツォン・ラ (Post-doctoral research scientist, Max Planck Institute for Chemical Physics of Solids, Germany)

I will be a new member of RIKEN iTHEMS and work on theoretical study in condensed matter.  In this short coffee meeting, I would like to disuss the topology properties of photocurrent. Firstly, based on band theory, I will discuss the topological classification of crystalline materials. Secondly,  Similar to direct current formular  I=U/R, the photocurrents will be discussed. Finally, I will discuss the topology properties of photocurrent in the various topological semimetals.

2021-05-21

Cosmology 101 - expanding universe and inflationary cosmology

難波 亮 (理化学研究所 数理創造プログラム (iTHEMS) 上級研究員)

I am a new member of RIKEN iTHEMS and working on several aspects of theoretical cosmology. As a partial self-introduction and introduction to the field, I would like to discuss some basics of cosmology, making it accessible by the iTHEMS members in different areas of expertise. In this short coffee meeting talk, my main focus is the evolution of the universe and the physics during its earliest period.

2021-05-14

Reducing complexity and pursuing reality in computational biophysics

杉田 有治 (理化学研究所 数理創造プログラム (iTHEMS) 上級研究員 / 理化学研究所 開拓研究本部 (CPR) 杉田理論分子科学研究室 主任研究員)

The basic unit of all the living matters is a cell, where huge number of biomolecules exist and express their biological functions. When we aim to study biological systems in computational biophysics, we always encounter many problems originated from the complexity of the systems. Reducing complexity has been one of the most essential issues in computational biophysics, while too much simplifications may lose the reality of biological phenomena. I would like to discuss several key mathematical concepts that have been used in computational biophysics for reducing complexity and pursuing reality of biology in the cell.

2021-04-30

Computational phases of quantum matter

松浦 俊司 (理化学研究所 数理創造プログラム (iTHEMS) 客員研究員 / Fundamental Researcher, Quantum Simulation Division, 1QBit, Canada)

I will talked about a connection between measurement-based quantum computing and quantum phases in physics.

2021-04-23

Building something from nothing: a mathematical framework for aperiodic/amorphous sets

クリストファー・ボーン (理化学研究所 数理創造プログラム (iTHEMS) 客員研究員 / 東北大学 材料科学高等研究所 (AIMR) 助教)

I will introduce a mathematical construction due to Bellissard that allows us to study disordered materials via Delone sets.

2021-04-16

Density Functional Theory from Functional Renormalization Group

横田 猛 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員 / 東京大学 物性研究所 特別研究員)

In this talk, I will give a brief introduction of density functional theory. I will also talk about our recent attempt to improve density functional theory for electron systems by use of the functional renormalization group.

2021-04-02

Spin transport in ultracold atomic superfluids

関野 裕太 (理化学研究所 数理創造プログラム (iTHEMS) 訪問研究員)

I will briefly introduce transport phenomena of spin in ultracold atomic gases in a superfluid phase

2021-03-26

Hunting the standard candles in their own nest

マリア・ジョヴァンナ・ダイノッティ (NAOJ/Space Science Institute)

I will introduce briefly the concept of Standard candles and how Gamma-Ray Bursts can be used as standardized candles through a new three-dimensional relation among important features of GRBs and how the kilonovae events associated with GRBs form a plane can naturally form a different plane with a much smaller dispersion around the plane.

2021-03-19

Sensitivity and robustness of chemical reaction network systems

岡田 崇 (理化学研究所 数理創造プログラム (iTHEMS) 上級研究員)

In living cellls, many reactions occur and form complex networks, such as metabolic networks. I will discuss how biological functions can emerge from the complex network dynamics, from network topology perspectives.

2021-03-12

Recent progress in black hole information paradox

後藤 郁夏人 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員)

2021-02-26

Fermionic transport under gravity

Kazuya Mameda (QHP)

I will briefly talk about transport phenomena induced by a background gravitational field.

2021-02-19

information scrambling is growth of wormwhole

野﨑 雅弘 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員)

I will explain what is the information scrambling, why it is important, and how it is related to the growth of wormhole.

2021-02-12

Active and Passive Phase Separation in a Lattice Model

足立 景亮 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員 / 理化学研究所 生命機能科学研究センター (BDR) 生体非平衡物理学理研白眉研究チーム 基礎科学特別研究員)

Phase separation is spontaneous segregation into high-density and low-density phases, observed in a variety of systems, e.g., alloy, polymer solution, and intracellular cytoplasm. In this talk, I will review the phase separation phenomena and introduce a model that connects the equilibrium phase separation to another class of separation driven by motility.

2021-02-05

Toward the standard model of elementary particles -- a brief history in 15 min. --

初田 哲男 (理化学研究所 数理創造プログラム (iTHEMS) プログラムディレクター)

I will make a very brief overview on the path toward the modern understanding on the law(s) of fundamental particles.

2021-01-29

Mathematical analysis to smoldering combustion

小林 俊介 (理化学研究所 数理創造プログラム (iTHEMS) 客員研究員 / 京都大学 大学院理学研究科 附属サイエンス連携探索センター (SACRA) 特定助教)

Recently, experimental and theoretical study on near-floor flame spreading along a thin solid have been reported. In this talk, I would like to introduce a mathematical model for flame/smoldering fronts, which is equivalent to the Kuramoto--Sivashinsky equation in a scale.

2021-01-22

Is a vacuum empty?

多田 司 (理化学研究所 数理創造プログラム (iTHEMS) コーディネーター / 理化学研究所 仁科加速器科学研究センター (RNC) 量子ハドロン物理学研究室 副主任研究員)

Usually, a vacuum is a word associated with nothingness. The modern concept of the vacuum, however, exhibits rich and beautiful structure. I will explain the vacuum is the very foundation of our universe.

2021-01-15

Revealing the Neutron Star Properties from Gravitional Wave

黄 永嘉 (理化学研究所 数理創造プログラム (iTHEMS) 国際プログラム・アソシエイト / Ph.D. Student, University of Science and Technology of China, China)

The gravitational wave detection brings us new opportunities to measure the neutron stars' properties. In this talk, I will briefly introduce the process of binary neutron star merger and what we could know from gravitational wave.