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International Symposium on Quantum Fluids and Solids (QFS)

2018年7月25日(水) - 31日(火)

The International Symposium on Quantum Fluids and Solids (QFS) will be held at Ito International Research Center (IIRC) on Hongo campus of the University of Tokyo, Japan, from July 25 through 31, 2018. One of the sponsors of this conference is iTHEMS. The QFS series started forty-three years ago making it one of the oldest series of international conferences in the field of low temperature physics. It has historically been focusing on physics of liquid and solid helium and hydrogen. But in this century its scope is expanding widely from laser cooled cold atoms to topological matters. At QFS2018 in Tokyo, this trend will be continued and with even more interdisciplinary aspects emphasized between the traditional subjects and those in broader physical systems.

会場: 東京大学 本郷キャンパス 伊藤国際学術研究センター

イベント公式言語: 英語

Bell's Theorem, Entanglement, Quantum Teleportation and All That

2018年7月19日(木) 16:00 - 17:30

Anthony James Leggett (Professor, University of Illinois at Urbana-Champaign, USA)

iTHEMS-CEMS Joint Colloquium. Professor Leggett is widely recognized as a world leader in the theory of low-temperature physics, and his pioneering work on superfluidity was recognized by the 2003 Nobel Prize in Physics. Abstract: One of the most surprising aspects of quantum mechanics is that under certain circumstances it does not allow individual physical systems, even when isolated, to possess properties in their own right. This feature, first clearly appreciated by John Bell in 1964, has over the last half-century been tested experimentally and found (in most people's opinion) to be spectacularly confirmed. More recently it has been realized that it permits various operations which are classically impossible, such as "teleportation" and secure-in-principle cryptography. This talk is a very basic introduction to the subject, which requires only elementary quantum mechanics.

会場: 大河内記念ホール

配信:計算科学研究棟 311会議室 / SUURI-COOL (Kyoto) / 東北大学 AIMR本館 2階セミナー室

イベント公式言語: 英語

Introduction to topological band structure

2018年7月6日(金) 10:30 - 17:30

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

In this seminar, I give an introduction to topological band structures. Topological band structure is the fundamental idea to understand phenomena such as the quantum Hall effect, topological insulators, and topological superconductors. Although originally found in fermionic electron systems, topological band structure is essentially a single-particle property, and thus the same phenomenon can arise also in bosonic systems. In fact, topological band structure does not even need quantum mechanics; topological band structure can arise in classical waves inside a periodic medium, such as electromagnetic waves or classical mechanical waves. In this seminar, I first give a brief introduction to key concepts in topological band structures, such as Berry curvature, Chern number, bulk-edge correspondence, and ten-fold way classification of topological insulators. I then explain how topological band structure can arise in classical systems, giving a brief introduction to the field of topological photonics and topological mechanics.

会場: セミナー室 (160号室)

イベント公式言語: 日本語

Topological Photonics and the four-dimensional quantum Hall effect

2018年7月3日(火) 15:00 - 17:00

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

In this seminar, I will give an introduction to topological photonics, that is, the study of topological band structures and resulting topological phenomena in photonic systems. I will first review basic concepts of topological band structures, and then explain what it means to realize topological band structures in photonic systems. I will particularly emphasize some important differences with respect to solid-state electron systems. I then present some of my own works in topological photonics, such as the synthetic dimensions in photonic systems, which allows one to explore models and phenomena in high dimensions including the four-dimensional quantum Hall effect.

会場: 東北大学 AIMR本館 1階会議室

イベント公式言語: 英語

デンソーITラボ - 理研 産学連携交流会

2018年6月29日(金) 16:00 - 17:40

16:00-17:00 デンソーITラボ 「ITラボの会社紹介」CTO岩崎弘利 「人とクルマの会話インタラクション」シニアリサーチャ 塚原裕史 「機械学習とコンピュータビジョンにも役立つ数学」リサーチャ 石川康太 17:00-17:40 理化学研究所 「古典物理と量子物理を結ぶ数理：古典系での量子ホール効果」iTHEMS上級研究員 小澤知己 「新粒子「ダイオメガ」－スパコン「京」と数理で予言するクォーク6個の新世界－」RNC基礎科学特別研究員 権業慎也

会場: コモンルーム (246-248号室)

イベント公式言語: 日本語

1-form Lieb-Schultz-Mattis theorem and anomaly matching in quantum dimer model

2018年6月8日(金) 13:30 - 17:00

菊池 勇太 (理化学研究所 仁科加速器科学研究センター (RNC) 理研BNL研究センター 理論研究グループ 理研BNLセンター研究員)

The Lieb-Schultz-Mattis theorem dictates that a trivial symmetric insulator in lattice models is prohibited if lattice translation symmetry and U(1) charge conservation are both preserved. In this talk, we discuss the generalization of the Lieb-Schultz-Mattis theorem to systems with higher-form symmetries, which act on extended objects of dimension n > 0. The prototypical lattice system with higher-form symmetry is the pure abelian lattice gauge theory whose action consists only of the field strength. We first construct the higher-form generalization of the Lieb-Schultz-Mattis theorem with a proof. We then apply it to the U(1) lattice gauge theory description of the quantum dimer model on bipartite lattices. Finally, using the continuum field theory description in the vicinity of the Rokhsar-Kivelson point of the quantum dimer model, we diagnose and compute the mixed ’t Hooft anomaly corresponding to the higher-form Lieb-Schultz-Mattis theorem.

会場: SUURI-COOL (Kyoto)

イベント公式言語: 日本語

Abelian-Higgs dualities in quantum defect-mediated melting phase transitions

2018年4月27日(金) 14:30 - 17:30

Aron Beekman (慶應義塾大学)

In the study of zero-temperature quantum phase transitions, instead of looking how symmetry is broken, it is often useful to see how symmetry can be restored by the condensation of topological defects. Through a duality mapping, Nambu-Goldstone modes are represented as gauge bosons, mediating long-range interactions between topological defects. When the latter condense, those bosons get as mass via the Anderson-Higgs mechanism, which signals the loss of rigidity and the restoration of symmetry. I will first review the best-studied case: the 2+1D superfluid-insulator transitions where the defects are U(1) vortices. Consecutively several extensions are discussed: going to 3+1D where the defects are not point particles but strings, and quantum elasticity, which studies breaking of spatial translations and rotations.

会場: セミナー室 (160号室)

イベント公式言語: 英語

Resurgence Theory for Non-Perturbative Quantum Analysis

2018年3月28日(水) 13:00 - 15:00

三角 樹弘 (理化学研究所 数理創造プログラム (iTHEMS) 客員研究員 / 秋田大学 専任講師)

会場: セミナー室 (160号室)

イベント公式言語: 英語

Recent Developments in QCD and Quantum Field Theories

2017年11月9日(木) - 12日(日)

This workshop covers a broad range of recent developments in QCD and quantum field theories involving perturbative QCD (with applications in the nucleon structure and heavy ion collisions), AdS/CFT correspondence and non-perturbative physics, lattice QCD, nucleon and nuclear structures and reactions, quantum field theory at finite temperature/density, the theory of cold atoms, and anomalous effects such as chiral magnetic/vortical effects rooted in quantum anomalies and topology. The primary goal of the workshop is to gather researchers in the relevant fields to exchange ideas and establish future collaborations. RIKEN - Taiwan Workshop

イベント公式言語: 英語

Introduction to topological quantum computing

2017年7月28日(金) 15:00 - 16:30

Zhenghan Wang (University of California Santa Barbara, USA)

第22回iTHES理論科学コロキウム

会場: 鈴木梅太郎記念ホール

イベント公式言語: 英語

Homological algebra, Renormalization and Transversality

2017年6月26日(月) 10:30 - 11:30

深谷 賢治 (Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)

Transversality is a basic concept of differential topology and theory of manifold. Homological algebra may be regarded as a method to approximate `spaces' by an algebra and is a basic concept in agebraic topology. I would like to explain in this talk how they are related to some basic problem of quantum field theory such as renormalization. Cosponsored by RIKEN iTHEMS and AIP Mathematical Science Team

会場: 理化学研究所 東京連絡事務所

イベント公式言語: 英語

Interdisciplinary symposium on modern density functional theory

2017年6月19日(月) - 23日(金)

Density functional theory (DFT) is one of the most widely used methods for quantum many-body problems in condensed matter, nuclear physics, and quantum chemistry. Although we share similar theoretical frameworks and computational techniques, we sometimes use quite different languages, which sets a certain barrier for efficient interdisciplinary collaborations on modern DFT, in particular, that powered by High Performance Computing Infrastructure (HPCI). The key idea of this symposium is to have intensive interdisciplinary discussions and to initiate a new collaboration platform, in particular, by introducing the basic methodology and highlighting the latest hot topics in the fields condensed matter, nuclear physics, and quantum chemistry. iTHEMS-AICS-RNC-U.Tokyo joint symposium

会場: 大河内記念ホール

イベント公式言語: 英語

Atypicality of most few-body observables

2017年5月29日(月) 13:30 - 14:30

濱崎 立資 (東京大学)

Understanding how isolated quantum systems thermalize has recently gathered renewed interest among theorists, thanks to the experimental realizations of such systems. The eigenstate thermalization hypothesis (ETH) is particularly investigated as a sufficient condition for the approach to thermal equilibrium. It states that diagonal matrix elements of an observable for the energy eigenstates are almost the same within a small energy shell. The ETH is justified for an observable and a Hamiltonian whose respective eigenbases are typically oriented to each other; i.e., for almost all unitary transformations of these two eigenbases with respect to the uniform Haar measure. In this seminar, we consider a Hamiltonian with few-body interactions and random observables without assuming the uniform Haar measure. These observables are chosen in an operational manner as random linear combinations of the operator basis of spins. We show that most few-body observables have atypical matrix elements when the energy width is not exponentially small with the system size. Namely, the maximum fluctuation for diagonal matrix elements is larger than that predicted by the uniform Haar measure.

会場: 研究本館 433号室

イベント公式言語: 英語

Geometry in condensed matter physics

2017年4月8日(土) 13:00 - 14:00

永長 直人 (理化学研究所 創発物性科学研究センター (CEMS) 強相関理論研究グループ 副センター長, グループディレクター / 東京大学 大学院工学系研究科 物理工学専攻 教授)

Quantum geometry plays essential roles current condensed matter physics. Aharonov-Bohm effect and Berry phase as its generalization are the key concepts in electronic systems in solids, which are described by the Bloch wavefunctions and electron correlation effects on top of them. In this talk, I will describe how the geometry determines the physical properties of materials focising on the gauge structure and electomagnetic responses.

会場: セミナー室 (160号室)

イベント公式言語: 英語

Fatgraph models for RNA molecules

2017年3月23日(木) 10:30 - 11:30

藤 博之 (香川大学 教育学部 准教授)

Concepts of fatgraphs and partial chord diagrams occur in many branches of mathematics, including topology, geometry, and representation theory. During the last decade, some applications of these mathematical objects to the research of the molecular biology have been reported. Among them, in particular, a characterization by the genus in the fatgraph presentation of the RNA has been studied remarkably. In this talk, I will explain how the concepts of fatgraphs and partial chord diagrams are applied to the study of the secondary structure of the RNA with pseudoknots, and introduce the matrix model that is invented by basic techniques of the quantum field theory. If time permits, I shall discuss about the matrix model of the protein, and speculate about further developments.

会場: セミナー室 (160号室)

イベント公式言語: 英語

低燃費タイヤ開発への量子ビーム応用

2017年2月23日(木) 15:00 - 17:00

岸本 浩道 (住友ゴム工業株式会社)

第13回iTHES産学連携数理レクチャー 世界的な環境への関心が高まる中、低燃費タイヤの開発が重要となっている。さらに、自動車需要が増加に伴い持続可能社会形成に重要となってくるのが省資源化の技術である。しかし、グリップ性能・低燃費性能・耐摩耗性能は相反関係にある。これら全ての性能を向上させるために量子ビームを用いた研究成果について紹介する。

会場: 大河内記念ホール

イベント公式言語: 日本語

量子アニーリングによる量子計算

2017年1月27日(金) 15:00 - 16:30

西森 秀稔 (東京工業大学 教授)

第19回iTHES理論科学コロキウム

会場: 大河内記念ホール

イベント公式言語: 英語

Non-perturabative quantum analysis based on resurgence theory

2016年11月11日(金) 10:30 - 11:30

三角 樹弘 (秋田大学 専任講師)

常微分方程式論においては，漸近展開に基づく形式的解から完全な解を構成するための理論体系「Resurgence理論」が確立されており，そこでは漸近級数ボレル和の総和として解が与えられる．一方，Resurgence理論を経路積分形式での量子論に適用することで，非摂動的に理論を解析する道が開ける．しかし，その際には「摂動級数の高次」と「古典作用の停留点」という2つの要素を手に入れる必要がある．実は，Resurgence理論は変数の複素化に伴う「ストークス現象」に基づくことから，ここでの停留点には実古典解だけでなく複素古典解も含まれる．したがって，Resurgence理論の量子論への応用においては，理論の複素古典解を求めその寄与を取り入れることが重要になる．このレクチャーでは，摂動級数と複素解に基づいた非摂動的解析法の理解を目標として，以下の順序で議論を進める．

会場: セミナー室 (160号室)

イベント公式言語: 日本語