STAMP seminar

"Resurgence Theory for Non-Perturbative Quantum Analysis"
by Tatsuhiro Misumi (Akita University)

Date: Mar 28 (Wed) 13:00 - 18:00
Place: Main Research bldg. 160

STAMP seminar

"Introduction to exact WKB analysis"
by Kohei Iwaki (Nagoya University)

Date: Mar 27 (Tue) 10:00 - 18:00
Place: Main Research bldg. 160

Special Lecture

"The Past and Future Accelerators in Nuclear Physics (around me)"

The lecturer: Prof. Shoji Nagamiya
Date & Time: 15:30~ March 20th 2018
Venue: 2F Large Meeting Room, RIBF Building

The lecture will be given in English.

STAMP seminar

"Anomaly matching for spin chains"
by Yuya Tanizaki (RIKEN BNL Research Center)

Date: Mar 19 (Mon) 14:00 - 17:00
Place: Main Research bldg. 160

Lectures on the knot theory
by Yuka Kotorii.
Room160 of Main Research Building of RIKEN Wako.

Wednesday March 14, 10:30- 14th Lecture

Number Theory Seminar

"Several identities related to the degenerate Bernoulli polynomials and numbers"
by Prof. Dr. Takao Komatsu (Wuhan University)

Date: February 24, 2018 (Sat) 16:00- (approximately until 17:00)
Venue: RIKEN Wako main research building room 160

Abstract: In this talk we demonstrate some relations in degenerate Bernoulli polynomials, which may be expressed as a general convolution identity. We also show some properties of hypergeometric degenerate Bernoulli polynomials and numbers.

Number Theory Seminar

"Diophantine Frobenius Problems -- counting theory, generating function and zeta functions"
by Prof. Dr. Takao Komatsu (Wuhan University)

Date: February 23, 2018 (Fri) 16:00- (approximately until 17:00)
Venue: RIKEN Wako main research building room 160

Abstract: When a_1, ...,a_m are relatively prime positive integers, the number of solutions of the linear Diophantine equation a_1 x_1 + … + a_m x_m = b in non-negative integers x_1, ...,x_m, for any integer b, is our concern. We show several formulas to give the largest integer b without solution. Then we discuss the generating function of the number of solutions. Finally, we derive an explicit expression for an inverse power series over the gaps values of numerical semigroups generated by two integers. It implies a set of new identities for the Hurwitz zeta function.

Lectures on the knot theory
by Yuka Kotorii.
Room160 of Main Research Building of RIKEN Wako.

Monday February 19, 13:30-  11th Lecture
Friday February 23, 13:30-  12th Lecture

iTHEMS Seminar

Date: Jan 22 (Mon), 2018, 14:00~
Venue: 246-248, main research building, RIKEN Wako

"Statistical mechanics of tissue homeostasis"
Kyogo Kawaguchi (Postdoctoral Research Fellow, Harvard University)

Adult tissues undergo rapid turnover as mature cells are continuously lost and new cells arise through cell division. The balance between the gain and loss of cells must be finely orchestrated to maintain tissues, but how this balance is achieved remains largely unknown. Previous works [1] have used universal scaling laws to claim that the fate choice of stem cells (division
or differentiation) are made strictly cell-autonomously. However, we recently recorded every stem cell fate choice within the mouse skin epidermal regions over one week and found that, far from being cell-autonomous, stem cell loss by differentiation is compensated by direct neighboring division [2].

In this talk, I will describe a model of tissue homeostasis using a macroscopic nonequilibrium setup, and explain how the coarse-graining of this model will lead to the effective dynamics of the voter model (DP2). I will show how we can use the property of dynamical crossover in the model -from the cell-autonomous regime (critical birth-death model) to the fate-coordinated regime (voter model)- to measure the length and time scales of stem cell coordination. I will then explain the pitfall in two-dimensions of  using scaling relations for the clonal fate trace of cells, and present the workaround we used in the data analysis to definitively show the existence of cell-to-cell fate correlation.

[1] E. Clayton et al., Nature 446, 185 (2007)
[2] K. Mesa, K. Kawaguchi et al., bioRxiv:155408 (2017)

iTHEMS Seminar/Theoretical Biology Seminar

Date: Jan 17 (wed), 2018, 13:30~
Venue: S406 of Bioscience Building, RIKEN Wako
http://www.riken.jp/en/access/wako-map/#campus_map (Bioscience Build is S01 in the map.)

"Spite theory in metapopulations and its application to dispersal and sex allocation"
Ryosuke Iritani (Research Fellow, University of California, Berkeley, US; University of Exeter, UK)

Elucidating the emergence of altruism has been central to social evolution theory. Recent studies have demonstrated that "spite", or harming other individuals at a fitness cost to self, is the opposite side of the same coin with altruism (Hamilton 1970, Wilson 1975, Gardner & West 2006, Lehmann et al. 2006), and in the presence of dispersal, spite is often more readily to evolve than is altruism (El Mouden & Gardner 2008). In this talk, I outline the spite theory, and conceptualize two biological scenarios based on spite theory: first, in the presence of parasites (or infectious diseases) in structured environments, hosts can utilize the disease as a biological weapon by dispersing across space. Second, in the presence of local mate competition (Hamilton 1967), in which competition for mating opportunity occurs with relatives, producing a predominantly higher proportion of males (over females) can harm other individuals. Critically, these two models offer testable predictions in terms of Hamilton's rule. I finally highlight future avenues to motivate empirical and experimental investigations.

iTHES Workshop

“The Kontsevish invariant and its ramifications”

Date: January 6-7, 2018
Venue: IIB Building, RIKEN Kobe site

This workshop aims to study Kontsevish invariant in Knot theory.
This topic has relation to quantum invariants and Vassiliev invariants.
This work shop will be conducted in Japanese.

Yuka Kotorii (RIKEN iTHES)  
Tetsuya  Abe (Ritsumeikan University)

SUURI-COOL seminar

All the following seminars will be taken place at
SUURI-COOL, 2F, Maskawa Build. for Education and Research, Kyoto University.

Date: December 27th (Wed.), 10:30-
Speaker: Yosuke Kubota
Title:  "Topology of linear operators and topological insulators"
Date: December 27th (Wed.), 13:30-
Speaker: Noriaki Ogawa
Title:  "Mathematical Modeling of Retinal Cellular Mosaic Pattern Formation"
Date: December 27th (Wed.), 16:00-
Speaker: Gen Kurosawa
Title:  "Theoretical study on the universality in biological clock and its species-specificity"
Date: December 28th (Thu.), 10:30-
Speaker: Shun Furusawa
Title:  "Compact-star phenomena and equation of state"


Supported by iTHEMS

Date: Dec. 26, (Tue) 15:00-
Venue: Kyoto University

Special iTHEMS Seminar

"Chiral Phases in Frustrated 2D Antiferromagnets and Fractional Chern Insulators"
Prof. Eduardo Fradkin
(Director, Institute for Condensed Matter Theory
Department of Physics,Univ. of Illinois
Date: Dec.21 (Thur.)  11:00am -
Venue: Main Research Building 5th-floor (535,537)

Abstract: The problem of topological phases of matter is one of the most fascinating open questions in theoretical physics. In this seminar I will discuss recent advances in the theory of topological phases in 2D systems. A key tool for these studies is a lattice version of Chern-Simons gauge theory. In particular its application to the problem of chiral phases in magnetization plateaus of spin 1/2 quantum antiferromagnets on the Kagome lattice and of fractional Chern insulators. The role of topology in the effective field theory and fractionalization of translation symmetries will be discussed.

Special iTHES/iTHEMS Introductory Lecture

"ABC conjecture and its proof"
Y. Miyaszaki (ithes-math team)
Date: Dec. 21 (Thurs.) 14:00-15:00
Venue: room 160 in the main research building
Language: Japanese

​For every ε > 0, there exist only finitely many triples (a, b, c)
of coprime positive integers with a + b = c such that q(a, b, c) > 1 + ε​,
where q(a,b,c)=log(c)/log(rad(abc)).​

RIKEN Symposium・iTHES/iTHEMS Workshop
"Frontiers of nonequilibrium physics—Particle physics, cosmology, and condensed matter—"

Date: Dec. 6th (Wed.)—Dec. 8th (Fri), 2017
Place: RIKEN Suzuki Umetaro Hall, Wakoshi, Saitama

"Nonequilibrium physics" for systems far from equilibrium remains still a frontier of sciences though we encounter it in broad branches of physics from particle/nuclear physics and astrophysics to condensed matter physics. The recent development of experimental techniques and numerical simulations enables us to accumulate a lot of interesting experimental/numerical results and brings about great progress within each area of physics. Nevertheless, these theoretical developments are not spreading out beyond their fields, and we do not have strong interaction instead of the common notion of “nonequilibrium physics”. This workshop is organized to extend and deepen our knowledge for nonequilibrium systems by reviewing and discussing the theoretical developments in various fields of physics from particle/nuclear physics and cosmology, to condensed matter.

Nonequilibrium physics
 - Nonequilibrium statistical physics
 - Cold atomic systems
 - Quantum open system
 - Transport phenomena
 - Application to cosmology/nuclear and hadron physics

R-ASTRO seminar

Date: 6th Dec., 16:00-
Place: Nishina Center

1.- Gravitational Wave event GW170817
2.- Short GRB GRB170817A; is it unique or not
3.- Optical kilo-nova SSS17a and R-process nucleosynthesis
4.- MAXI upper limits and Chandra detection
5.- Relations to recent RIBF results
6.- Constraints on the nuclear EOS

1. Oliver Just (he will mention about his research on SGRBs+R-Nuclei, too)
2. Toru Tamagawa (Obs.) Hirotaka Ito (Theory side)
3. Susumu Inoue
4. MAXI team
5. Shunji Nishimura
6. Shun Furusawa

Each presentation should be less than 10 mins (about 5 mins, using
a few slides). Discussions are followed after the presentation for
each topic.

STAMP seminar

"Cosmological Constant Problem and Scale Invariance"
by Taichiro Kugo (Kyoto Sangyo University)

Date: Dec 5 (Tue) 14:30 - 16:00
Place: Main Research bldg. 433

   We show that the long standing cosmological constant problem may be resolved very naturally if our world is scale invariant. The most essential difficulty of the cosmological constant problem resides in the fact that there are multiple and hierarchical spontaneous symmetry breakings in nature below the Planck energy: The vacuum condensation energies associated with each spontaneous breaking, extending over wide ranges of energy scales, are automatically and almost completely cancelled at each step of the spontaneous symmetry breaking. Classical scale invariance gives a natural mechanism for causing such a miracle. We give an argument that the quantum anomaly for scale invariance does not injure this vanishing property of the potential value at at the stationary point.

"Data Assimilation School (Basics)"

Date: Dec.4(Mon.)-Dec.8(Fri.), 2017
Place:  RIKEN AICS and Nichii-gakkan Kobe
Registration deadline: Oct.31 (Tues.)  2017

Hosted by RIKEN AICS
Co-hosted by RIKEN iTHES and Kyoto MACS Program

iTHEMS Special Lecture

Date: December 1, 2017 15:00-
Venue: Suzuki Umetaro Hall, RIKEN Wako Campus
Lecturer: Dr. Shigeru Kuratani (Chief Scientist, RIKEN Center for Developmental Biology)

We are pleased to announce that the iTHEMS lecture by Dr. Shigeru Kuratani will be held on December 1st. Dr. Kuratani has been known as a prominent researcher in evolutionary biology. Also, he has published many books intended for general readership including the one about “Godzilla” and its biological origin. This time, he will give a lecture for non-biologists as well as for biologists. So, please feel free to join. The tile of his talk is "Development and Evolution”. The talk is in Japanese.

iTHES  seminar

"A New Look at Matrix Models for QCD3"
Dr. Takuya Kanazawa (RIKEN iTHES)
Date: November 24 (Friday), 2017 16:30-
Venue: Room 160 of Main Research Building, RIKEN (Wako Campus)

Abstract: Non-chiral random matrix models for QCD
in 2+1 dimensions and their new generalizations will
be discussed.

iTHEMS seminar

"Mathematical analysis of DNA unlinking by XerCD-FtsK"
by Prof. Koya Shimokawa (Saitama University)

Date: November 20 (Monday), 2017 10:30-
Venue: Room 160 of Main Research Building, RIKEN (Wako Campus)

In 2007, Grainge et al. showed that, when coupled with FtsK, the site-specific recombinases XerC/XerD can unlink DNA catenanes and proposed a stepwise model of unlinking. We show that their model is the only pathway from the 2m-cat to the unlink when we assume each recombination event reduces the crossing number. We also characterize shortest pathways from the 6-cat to the unlink under the assumption that the crossing number does not increase at each event.

Theoretical Biology Seminar/ iTHES Seminar

November 17, 2017 14:00-
“What enables mammalian hibernation?”
Dr. Yoshifumi Yamaguchi (University of Tokyo)
Venue: S406, Bioscience Building

Some animals including bears and squirrels become dormant (inactive) during winter.
It is called “hibernation" and little is known about it.
Yamaguchi-san has challenged the mechanism of hibernation,
and he is already a leading researcher in the field although he is still young.

The seminar is not only for biologists but also for non biologists.
The seminar will be given in Japanese.

Lectures on the knot theory
by Yuka Kotorii.
Room160 of Main Research Building of RIKEN Wako.

Thursday November 16, 13:30- Ninth Lecture
Tuesday November 21, 10:30- Tenth Lecture

Number Theory Seminar

"An asymptotic formula for the 2k-th power mean value of |L'/L(1+it_0,χ)|"
by Dr. Sumaia Saad Eddin (Nagoya University)

Date: November 15, 2017 (Wed) 15:30~ (approximately until 16:30)
Venue: RIKEN Wako main research building room 160

Abstract: “Title and abstract, 15.11.2017.pdf"

ABBL-iTHEMS Joint Workshop:
“Theories of Astrophysical Big Bangs”

Date: Nov. 13-17, 2017
Venue:  Room 246-248 in the main research building (Wako Campus, RIKEN)

We will have morning sessions 10:00-12:00 for discussions, and seminars from 15:00 everyday. Especially, we will have a seminar by Kipp Cannon on 15th Nov. He is a LIGO member and he is giving a talk on Gravitational Waves. Please feel free to join us.

RIKEN - Taiwan Workshop:
"Recent Developments in QCD and Quantum Field Theories"

Date: Nov. 9-12, 2017
Venue: National Taiwan Univ.

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.

ABBL-iTHEMS Joint Workshop:
“Theories of Astrophysical Big Bangs”

Date: Nov. 6-10, 2017
Venue:  Okochi Hall (Wako Campus, RIKEN)

We are pleased to announce an international workshop on Astrophysical Big Bangs, which will cover supernovae, supernova remnants, gamma-ray bursts, black holes, neutron stars, and high-energy astrophysics in general.  We are inviting numerous VIPs (very important collaborators and best friends) from around the world to give talks, and both current and past ABBL members are welcome to present their work.  The workshop will be held from November 6th to 10th, but we will also have one more week for free discussion (November 13th-17th).  During this second week, we plan to have casual discussion sessions in the morning and completely free afternoons; we would like to talk with our VIPs and ABBL alumni about ongoing and/or future collaborations.

Lectures on the knot theory
by Yuka Kotorii.
Room160 of Main Research Building of RIKEN Wako.

Tuesday October 31, 10:30- Seventh  Lecture
Thursday November 2, 13:30- Eighth Lecture

Special Lecture on
"The Dawn of the Gravitational Wave Astronomy and the Discovery of the Neutron Star Merger"
(The lecture is for no-specialist and is given in Japanese.)

Date and time: Oct. 31, 2017 (15:30-17:00)
Place: Okochi hall
S. Nagataki (ILs and iTHEMS)
S. Inoue (ILs ABBL lab.)
T. Tamagawa (Nishina Center)

iTHEMS Mini-workshop/ Theoretical Biology Mini-workshop

Date: October 19 (Thursday), 2017 14:00-
Venue: Okochi Hall, RIKEN Wako Campus

“Kazusa DNA Research Institute: Who is this?”
Dr. Satoshi Tabata (Kazusa DNA Res Inst, Director)

“Did the journey to strawberry start from Japan?”
Dr. Sachiko Isobe (Kazusa DNA Res Inst, Lab Head)

Abstract: Strawberry (Fragaria × ananassa) is cultivated and consumed across the world. It is an allo-polyploidy species (2n = 8X = 56) with an estimated genome size of 1C = 708–720 Mb. Strawberry was artificially generated in the 16th century Europe, by crossing between two octoploid species, F. chiloensis and F. virginiana. The evolutionary origin and genome structure have been discussed and not fully determined. The first proposed structure was AABBBBCC model (Federova, 1946), then, Senanayake and Bringhurst (1967) proposed AAA’A’BBBB model. The fully allopolyploidy structure (AAA’A’BBB’B’) was suggested by Bringhurst in 1990 based on isozyme segregation. This model was also supported by the segregation patterns of CAPS markers (Kunihisa et al. 2011) and SSR markers (Isobe et al. 2013). However, just recently, Tennessen et al. (2014) proposed the AvAvBiBiB1B1B2B2, model, according to the results of targeted DNA capture and sequencing by using next generation sequencing (NGS) technology. In this model, Av represents the most F. vesca like genome, while Bi represents the most F, iinmae like genome. The origin of F. vesca is considered as North America, and F. iinumae is an endemic species in Japan. Our resent results of denovo whole genome sequencing support the AvAvBiBiB1B1B2B2 model, that suggest considerable part of the strawberry genome showed the highest similarity with F. iinumae.

iTHES/iTHEMS seminar

"The Riemann-Roch theorem"
by Dr. Yosuke Kubota (iTHEMS, RIKEN)

Date: September 26 (Tuesday), 2017 14:00-
Venue: Room 160 of Main Research Building, RIKEN (Wako Campus)

In the mid- 19th century, B. Riemann introduced the notion of Riemann surface in his Ph.D thesis on complex analysis. Together with non-Euclidean geometry, the theory of Riemann surface is a germination of modern geometry in both algebraic and analytic sense. In this talk, I will give an introduction of the theory of Riemann surface centering around the Riemann-Roch theorem. It is an important prototype of the Atiyah-Singer index theorem, the starting point of my research field.

RIMS-iTHEMS International Workshop on Resurgence Theory

Dates: September 6-8, 2017
Place: RIKEN Kobe Campus, Integrated Innovation Building (IIB)

Resurgence theory and other related methods have recently attracted a great deal of attention in mathematics and theoretical physics. The purpose of this workshop is to bring both mathematicians and physicists together to accelerate progress in non-perturbative quantum analyses such as the resurgence theory. The topics to be discussed at the workshop include -Resurgence theory -Exact WKB analysis -Wall-crossing (Stokes) phenomena -Lefschetz thimble -Perturbative calculation for non-pert. physics -Functional renormalization group -Other non-perturbative methods. Although the workshop mainly consists of invited talks, we will have relatively long discussion time each day and welcome lots of people. We hope that this workshop will advance the research on non-perturbative quantum analysis and produce significant works.

For details, visit the following workshop site

Number Theory Seminar

"Connections of Pair Correlations to Equidistribution and Additive Energy"
by Thomas Lachmann (TU Graz)

Date: August 31 (Thu), 13:30~ (approximately until 15:00)
Venue: room 246-248 of main building, RIKEN (Wako branch)
(In case the room is not ready, we will hold the seminar at room 160.)

Abstract: (see attachment)

iTHES/iTHEMS seminar

"Pulsar Winds: Ultimate Relativistic Outflows"
by Dmitry Khangulyan from Rikkyo Univ.

Date: August 29th (Tue), 13:30-
Venue: R433 of the main research building

A highest density body that features the strongest magnetic field launches, no surprise, an ultimate outflow -- pulsar wind. Despite their relativistic nature and complexity, a few simple analogies can help us to understand the essence of pulsar physics. I will present several links connecting basic mechanics and electrodynamics, every-day thermodynamics and hydrodynamics to the processes taking place in the vicinity of pulsars. These fundamental relations not only provide a simple mental image for the pulsar physics but also have their imprint in high-energy data obtained from pulsars and pulsar wind nebulae.

iTHEMS Special Lecture "Encounter of Mathematics and Ancient History"

Date: August 24th (Thur.) 15:00 ~
Venue: Okochi Hall
Lecturer: Prof. Hiromichi Mori (Kyoto Sangyo Univ.)
Title: On the classification of the Chronicle of Japan (The lecture will be given in Japanese due to the subject, which is on the formation of the Chronicle of Japan.)

Theoretical Biology Seminar/ iTHEMS Seminar

"Do calcium buffers always slow down the propagation of calcium waves?"
by Prof. Je-Chiang Tsai (National Taiwan Normal University)

Date: July 24 (Monday), 2017 13:30-
Venue: Room 160 of Main Research Building, RIKEN (Wako Campus)

Calcium buffers are large proteins that act as binding sites for free cytosolic calcium. Since a large fraction of cytosolic calcium is bound to calcium buffers, calcium waves are widely observed under the condition that free cytosolic calcium is heavily buffered. In addition, all physiological buffered excitable systems contain multiple buffers with different affinities. It is thus important to understand the properties of waves in excitable systems with the inclusion of buffers.

There is an ongoing controversy about whether or not the addition of calcium buffers into the system always slows down the propagation of calcium waves. To solve this controversy, we incorporate the buffering effect into the generic excitable system, the FitzHugh-Nagumo model, to get the buffered FitzHugh-Nagumo model, and then to study the effect of the added buffer with large diffusivity on traveling waves of such a model in one spatial dimension. We can find a critical dissociation constant (K=K(a)) characterized by system excitability parameter $a$ such that calcium buffers can be classified into two types: weak buffers ($K\in(K(a),\infty)$) and strong buffers ($K\in(0,K(a))$). We analytically show that the addition of weak buffers or strong buffers but with its total concentration b(0)(1) below some critical total concentration b(0,c)(1) into the system can generate a traveling wave of the resulting system which propagates faster than that of the origin system, provided that the diffusivity D1 of the added buffers is sufficiently large. Further, the magnitude of the wave speed of traveling waves of the resulting system is proportional to $\sqrt{D_1}$ as $D_1\to\infty$. In contrast, the addition of strong buffers with the total concentration b(0)(1)>b(0,c)(1) into the system may not be able to support the formation of a biologically acceptable wave provided that the diffusivity D1 of the added buffers is sufficiently large.

Lectures on the knot theory
by Yuka Kotorii.
Room160 of Main Research Building of RIKEN Wako.

Monday July 24, 10:30- Fifth  Lecture
Wednesday    July 26, 10:30- Sixth Lecture

iTHES Seminar

Date&Time: 14:30~, July 21st (Fri.)
Venue: Rm. 435,437, Main Research Building
Speaker: Dr. Takahiro Sakaue  (Department of Physics, Kyushu University)
Title: "Structure and dynamics of nuclear chromosomes based on polymer physics"

The talk will be given in Japanese. The abstract in Japanese follows:

iTHEMS Joint Seminar with Condensed Matter Theory Laboratory

Speaker: Shinsei Ryu (Chicago)
Date & Time: July 20th (Thur.), 13:30~
Venue: Room 435, 437, Main Research Building

Title: Topological twist liquids in three spatial dimensions

iTHEMS seminar
"An invitation to number theory" by Hiroyasu Miyazaki (iTHES, RIKEN)
Date: July 10 (Mon), 2017 13:30-
Venue: Room 160 Main Research Building, RIKEN (Wako Campus)
Abstract: The goal of number theory is to reveal the mystery of natural numbers 1,2,3…. It has a long history, and it is still developing by exchanging ideas with many other branches of mathematics. In the long history, number theory had been thought of as a pure mathematics with no direct application outside mathematics. However, the rapid development of computer science changed the situation: the theory of prime numbers has been applied to code theory, cryptography, random number generation etc. It seems that there are several researches in physics and biology using the method of number theory, too. The aim of this talk is to give a beginner-friendly introduction to number theory. Among many topics, I will focus on very fundamental and important concepts: the “p-adic numbers” and the “finite fields.” I hope that this talk will motivate you to relate your research to number theory.

iTHEMS Workshop on Sine square deformation and related topics
Date: June 30, 2017 10:30 - June 30, 2017 17:00
Venue: Rm. 160, Main Research Building

Speakers include:
Shinsei Ryu (Chikago), Chisa Hotta (Tokyo), Toshiya Hikihara (Gunma), Hosho Katsura (Tokyo), Kouichi Okunishi (Niigata), Tsukasa Tada(RIKEN)

Organizers: Nobuyuki Ishibashi (Tsukuba), Hosho Katsura (Tokyo), Kouichi Okunishi (Niigata), Tsukasa Tada(RIKEN)



iTHEMS Seminar with AIP Mathematcial Science Team

Title: Homological algebra, Renormalization and Transversality
Speaker: Kenji Fukaya / 深谷賢治
Date:   June 26, 2017 10:30
Venue:   RIKEN Tokyo Liaison Office (Nihonbashi)

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 

 cosponsored by RIKEN iTHEMS and AIP Mathematical Science Team

"Interdisciplinary symposium on modern density functional theory"

June 19-23, 2017
Okochi hall, RIKEN (Wako Campus)


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.

List of keynote talks:
Condensed matter
E.K.U. Gross (Max Planck Institute, Germany)
Taisuke Ozaki (U. Tokyo, Japan)
Osamu Sugino (U. Tokyo, Japan)
Quantum chemistry
Kieron Burke (UC Irvine, US)
Takao Tsuneda (Yamanashi U., Japan)
Nuclear physics
Gianluca Colo (U. Milano, Italy)
Jie Meng (Peking U., China)
Takashi Nakatsukasa (U. Tsukuba, Japan)
Takaharu Otsuka (RIKEN, Japan)
Hadron physics
Wolfram Weise (TU Munich, Germany)

List of topical talks:
Condensed matter
Ryosuke Akashi (U. Tokyo, Japan)
Yu Kumagai (Tokyo Tech., Japan)
Jun'ichi Iwata (U. Tokyo, Japan)
Quantum chemistry
William Dawson (RIKEN, Japan)
Dmitri Fedorov (AIST, Japan)
Muneaki Kamiya (Gifu U., Japan)
Takehiro Yonehara (RIKEN, Japan)
Nuclear physics
Lu Guo (U. CAS, China)
Wenhui Long (Lanzhou U., China)
Yifei Niu (ELI-NP, Romania)

​Haozhao Liang (RIKEN Nishina Center/Univ. Tokyo)
Tetsuo Hatsuda (RIKEN iTHEMS)​
​Takahito Nakajima (RIKEN AICS)

Lectures on the knot theory
by Yuka Kotorii.
Room160 of Main Research Building of RIKEN Wako.

Wednesday June 14, 10:30- Third  Lecture
Friday    June 16, 10:30- Fourth Lecture

Date: Jun 02 (Fri)
Time: 14:30 -
Place: Main Research bldg. 160
Speaker: Dr. Satoshi Iso (KEK)

Title: On Unruh effect and the radiation stimulated by quantum entanglement

Abstract: Quantum entanglement of the Minkowski vacuum state between left and right Rindler wedges generates thermal behavior in the right Rindler wedge, which is known as the Unruh effect. In this talk, we first review the basics of the Unruh effect, and then show our recent discovery that there is another consequence of this entanglement; namely entanglement-induced quantum radiation emanating from a uniformly accelerated object. Though It seems to contradict to our intuition  that incoming and outgoing energy fluxes should cancel each other out in a thermalized state, we clarify why it is not so.

iTHES physics seminar

* Speaker:    Ryusuke Hamazaki (University of Tokyo)
* Place:    room 433, main research building
* Date:     Monday, 29 May, 13:30-
* Title:
  Atypicality of most few-body observables

* Abstract:
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.

Lectures on Knot Theory

Lecturer: Yuka Kotorii (iTHES)
Date & Time: May 29th, 10:30 ~ (First Lecture)
                      June 1st, 10:30~ (Second Lecture)

Venue: Rm. 160, Main Research Building

STAMP Seminar (in Japanese)

Title: Applications of the effective field theory method to inflation models
Lecturer: Toshifumi Noumi (Kobe U.)
Date & Time: 14:30~, May 26th (Fri.)
Venue: Rm. 160, Main Research Build.

iTHES/iTHEMS Seminar

May 25(Thu.) 10:30~
"Guiding principles to develop tough polymer materials: An exactly solvable model"
Dr. Naoyuki Sakumichi (Ochanomizu University)
Place: Rm. 160, Main Research Building

Needs to impart appropriate elasticity and high toughness to viscoelastic polymer materials are ubiquitous in industries such as concerning automobiles and medical devices. One of the major problems to overcome for toughening is catastrophic failure linked to a velocity jump [1-3], i.e., a sharp transition in the velocity of crack propagation occurred in a narrow range of the applied load.
However, its physical origin has remained an enigma despite previous studies [4] over 35 years. Here, we propose an exactly solvable model that exhibits the velocity jump incorporating linear viscoelasticity with a cutoff length for a continuum description [5]. With the exact solution, we elucidate the physical origin of the velocity jump: it emerges from a dynamic glass transition in the vicinity of the propagating crack tip. We further quantify the velocity jump together with slow- and fast-velocity regimes of crack propagation, which would stimulate the development of tough polymer materials.

[1] A. Kadir and A. G. Thomas, Rubber Chem. Technol. 54, 15 (1981).
[2] K. Tsunoda, et al., J. Mater. Sci. 35, 5187 (2000).
[3] Y. Morishita, et al., Phys. Rev. E 93, 043001 (2016); Polymer108,
230 (2017).
[4] e.g., G. Carbone and B. N. J. Persson, Phys. Rev. Lett. 95, 114301 (2005).
[5] N. Sakumichi and K. Okumura, arXiv:1611.04269.


iTHES Seminar

April 14th (Fri.) 14:30-
"Chaos, Quark, Black Hole"
Prof. Koji Hashimoto (Osaka University)
Place: Rm 160, main research building

iTHES/iTHEMS Seminar

April 11 (Tuesday) 15:30- 
Rm 433, Main Research Building
"HPC in precision medicine"
Prof. Tilo Wettig (Univ. Regensburg)

​In theoretical particle physics we have been using high-performance computing (HPC) for three decades to make scientific progress. Recent advances in next-generation sequencing, as well as the corresponding bioinformatics questions, generate an obvious need for HPC methods in the field of precision medicine. We have recently started to explore this field and believe that our HPC expertise can be used to speed up time-critical workflows, to better manage the large amount of data involved, and to lead to more cost- and energy-efficient solutions. I will discuss a few concrete examples, including interesting questions in single-cell sequencing.

Theoretical Biology Seminar

April 10th (Mon.) 13:30-
"Cell wall pattern formation in xylem vessels"
Dr. Yoshihisa Oda (National Institute of Genetics)
Place: S406, Bioscience Building

iTHES/iTHEMS Seminar

April 8 (Sat.) 13:00-
"Geometry in condensed matter physics"
Prof. N. Nagaosa
(RIKEN Center for Emergent Matter Science (CEMS), Department of Applied Physics, The University of Tokyo)
Place: RIKEN Wako campus, Main building 1st floor,  Room 160

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.

iTHES/iTHEMS Seminar

April 6 (Thu.) 10:30-
"The local time of simple random walks and Gaussian free fields in two dimensions"
OKADA, Izumi (Tokyo University of Science)
Place: Rm. 160, Main Research Building

By using the method of probability analysis, we have researched the local time of a multidimensional-simple random walk. Note that the local time means the number of visits of a simple random walk to specific points in integer lattice. It is known that functionals of a local time and Gaussian free fields denote a variety of nonlinear and mathematical phenomena such as random media. Then, we are observing the relationship between two processes.
As a first step, we especially observe favorite points (the singular sites where the local time is large) et al. By A.Dembo, Y.Peres, O.Zeitouni, J.Rosen, who are leading experts in this field, the importance of this point has been recently shown.


Seminar Information

March 29, 2017 14:00-15:30
"Mathematical analysis of persistence, permanence, and homeostasis in biological interaction networks"
Prof. Gheorghe Craciun
(Dept. of Mathematics and Dept. of Biomolecular Chemistry, Univ. of Wisconsin-Madison)
Place: Cooperation Center (研究交流棟) W319.321

Abstract: Many diseases are associated with the loss of some types of molecules in affected cells, and this loss can destabilize normal cellular processes. The recovery of these processes in affected cells is a potential therapeutic target.

We discuss a mathematical approach to understanding biological interaction networks, by using differential equations to model the dynamics of concentrations of various types of molecules involved in these networks.

Using this approach, we describe mathematical properties of these networks that may allow us to understand which types of biological feedbacks are essential for the stability of normal cellular processes.  More specifically, we discuss the mathematical properties of "persistence" and "permanence" that are very closely related to the stability and homeostasis properties of biological interaction networks.

The same approach can be used for analyzing the stability of very general population processes, for example to determine if various animal species may coexist in an ecosystem, or if an infectious disease may become endemic.

Contact: Yasushi Sako (sako@riken.jp <mailto:sako@riken.jp>)

iTHEMS Seminar

March 23 (Thu.) 10:30-
"Fatgraph models for RNA molecules"
Prof. FUJI, Hiroyuki (Kagawa Univ. & QGM, Aarhus Univ.)
Place: Rm. 160, Main Research Building
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.

[1] Jørgen Ellegaard Andersen, Hiroyuki Fuji, Robert C. Penner, and Christian M. Reidys, “The boundary length and point spectrum enumeration of partial chord diagrams using cut and join recursion,” Trav. Math. 25 (2017) 213-232, arXiv: 1612.06482 [math-ph]. 
[2] Jørgen Ellegaard Andersen, Hiroyuki Fuji, Masahide Manabe, Robert C. Penner, and Piotr Sułkowski, “Partial chord diagrams and matrix models,” Trav. Math. 25 (2017) 233-283, arXiv: 1612.05840 [math-ph]. 
[3] Jørgen Ellegaard Andersen, Hiroyuki Fuji, Masahide Manabe, Robert C. Penner, and Piotr Sułkowski, “Enumeration of chord diagrams via topological recursion and quantum curve techniques,” Trav. Math. 25 (2017) 285-323, arXiv: 1612.05839 [math-ph].

March 8 – 11, 2017
"International Workshop on Quantum Many-Body Problems in Particle, Nuclear and Atomic Physics"
​(​Duy Tan University, Danang city, Vietnam​)​

The workshop aims to discuss various topics in quantum many-body systems in particle, nuclear, and atomic physics. In particular, the workshop will cover topics on​ Lattice QCD, Physics of cold atoms​, Nuclear physics​ and Astrophysics​​​.

Nguyen Dinh Dang​ (RIKEN Nishina Center)
Tetsuo Hatsuda (RIKEN iTHES)​
Nguyen Quang Hung​​ (Duy Tan University​)​

March 4th, 2017
"Kobe iTHES workshop on Quantum Materials"

Venue: IIB Building, RIKEN Kobe site

The workshop will be conducted in Japanese.

Tetsuo Hatsuda (RIKEN iTHES & iTHEMS Director)
Takuya Kanazawa (RIKEN iTHES)
Shun Uchino (RIKEN CEMS)

Theoretical Biology Seminar/ iTHES Seminar

March 1st, 2017 15:00-
"Mechanics of epithelial morphogenesis"
Dr. Shigeo Hayashi
(RIKEN Center for Developmental Biology)
Venue: 2F Large Meeting Room in Wako Main Cafeteria, RIKEN

The epithelium is the unit of animal tissues and its modification through elongation, folding, dissociation and re-association creates varieties of organ shapes and functions. Polarized epithelial cells are assembled into stable monolayers that are tightly associated with each other by cell-cell adhesion systems, and to extracellular substrates via cell-extracellular matrix (ECM) adhesion. Breaking stability of robustly assembled epithelia is the key steps of morphogenesis and the onset of pathogenic states. My laboratory studies core processes of epithelial tube morphogenesis in Drosophila using genetic and morphological approaches. I will explain how mechanical instability is actively exploited during epithelial folding. I will also show how such an instability is restricted during the formation of airway tubules with constant length and diameter to optimize circulation. Managing buckling instability in tissue architecture appears to be the key regulatory steps in morphogenesis.

Dec. 5–​8, 201​6​
iTHES-CEMS-RBRC-RNC workshop on "​Chiral Matter: from quarks to Dirac semimetals​"
​Place:​​ RIKEN Okochi Hall

This workshop shall be a valuable, first time occasion to bring together the expert practitioners in all three communities of condensed matter, QCD, and quantum field theory (AdS/CFT correspondence), under the same theme of novel phenomena deeply rooted in topology. The workshop aims at providing the participants with a unique indispensable opportunity to share ideas and insights on the novel topological phenomena from three different angles, potentially leading to synergistic advancement of this fast evolving field of physics.
Dmitri E. Kharzeev (RIKEN BNL Research Center / Stony Brook U., Chair)
Kenji Fukushima (The University of Tokyo)
Akira Furusaki (RIKEN iTHES / CEMS)
Tetsuo Hatsuda (RIKEN iTHES / RIKEN Nishina Center)
Naoto Nagaosa (RIKEN CEMS / The University of Tokyo)
Ho-Ung Yee (RIKEN / U. of Illinois)

​Supported by
iTHES http://ithes.science-server.com/
CEMS http://www.cems.riken.jp/en/
R​BRC https://www.bnl.gov/riken/
​RNC http://www.nishina.riken.go.jp/index_e.html​

Theoretical Biology Seminar/iTHES Seminar
“A mathematical model of delayed sleep phase type and PERIOD 3 variant”
Date: November 24, 1:30pm
Place: S406 of Bioscience Building
(Bioscience Building is S01 in the map above)
Speaker: Ms. Haru Negami (Graduate School of Engineering, The University of Tokyo)

The purpose of this study is elucidation of the mechanism of sleep disorder. Especially, we focus on a type of sleep disorder, delayed sleep phase type (DSPT), and its related gene, Per3. The problem is quite important because the number of the patients has been increasing and sleep disorder is said to cause more severe problems such as depression or other mental illnesses. At this seminar, we first demonstrate a synchronization system between daylight and clock gene expression, which is robust to seasonal fluctuations of daytime length, by combining the Goodwin model and state-dependent delayed feedback scheme. Then, we show the theoretically possible relationships between gene Per3 variant and circadian phenotype.
The symptoms of DSPT are the followings; delayed production of melatonin or delayed recovery of sleep after sleep deprivation. This symptom can be improved by melatonin administration or light exposure before sleep. Recent investigation elucidated the mutation at Per3 caused familial delayed sleep phase and is associated with a seasonal mood trait [1-4].
It is well known that exposure to the sunlight affects sleep cycle. However, Sivertsen et al. clarified that seasonal variation in sleep were not found at Latitude 63-65 degree in Norway where seasonal fluctuation of daytime is significant by large-scale (for 43,045 participants) study in 2011[5]. The fact indicates that human being attained a robust mechanism to maintain sleep cycle, although the physiological mechanism still remains unclear.
A state-dependent delayed differential equation was adopted to simplify the system to grasp its global structure and suggest a novel synchronization scheme and conditions by developing a 6-variable Goodwin model introduced by Matsumura et al. in 2014[6]. Here, we developed the model of Matsumura’s with additional two oscillators, daylight and melatonin. Oscillation of melatonin follows a differential equation with state-of-daylight- dependent delay. In addition, the level of mRNA of PER is regulated by melatonin which adjusts the reaction speed constant conditionally.

[1]  T. Ebisawa et al., ”Association of structural polymorphisms in the human period3 gene with delayed sleep phase syndrome.” EMBO rep 2: 342-6. (2001)
[2]  K. Shibui et al., ”Melatonin rhythms in delayed sleep phase syndrome.” J Biol Rhythms 14: 72-6(1999)
[3]  L. Zhang et al., ”A PERIOD3 variant causes a circadian phenotype and is associated with a seasonal mood trait.” Proc Natl Acad Sci USA 113(11):E1536-44 (2016)
[4]  M. Uchiyama, et al., ”Poor compensatory function for sleep loss as a pathogenic factor in patients with delayed sleep phase syndrome.” Sleep 23: 553-8 (2000)
[5]  B. Sivertsen, et al., ”Seasonal variations in sleep problems at latitude 63-65 in Norway: The Nord-Trondelag Health Study, 1995-1997.”, Am J Epidemiol 174(2),147-53 (2011)
[6]  R. Matsumura, et al., ”The Mammalian Circadian Clock Protein Period Counteracts Cryptochrome in Phosphorylation Dynamics of Circadian Locomotor Output Cycles Kaput (CLOCK)”, J Biol Chem 289(46):32064-72 (2014)

Nov. 18 (Fri) 2016, 15:00- ​**THIS FRIDAY!!**
​iTHES Special Symposium
"Harmony between Math and Nature"
Place: Suzuki Umetaro Hall (Wako, RIKEN)

15:00- 15:45
"Classification of Algebraic Manifolds"
Prof. Shigefumi Mori (Kyoto U., 1990 Fields Medal)

Music performance by RIKEN Music Club

"Discovery of Neutrino Oscillations"
Prof. Takaaki Kajita (Univ. Tokyo, 2005 Nobel Prize)

Feel free to join!
(The talks are in Japanese, while slides are in English).

hosted by iTHES
co-hosted by KUIAS and RIMS

"RIKEN Data Assimilation workshop"
Date: Oct.14 (Fri.) 10:00 am -
Place: AICS 1F seminar room
 Sponsored by AICS, co-sponsored by iTHES
Registration deadline: Oct.2
contact: da-ws-app(at)riken.jp

Theoretical Biology Seminar/iTHES Seminar
"Development and application of high-speed microscopes: super-resolution 4D-imaging and single-molecule counting”
Date: October 5 (wed.) 13:30-
Place: S406 of Bioscience Building
(Bioscience Building is S01 in the map above)
Speaker: Dr. Yasushi Okada (RIKEN QBiC and Dep. of Physics, U-Tokyo)

The 3rd Workshop for Extreme Materials Science
“Structure and Properties of Silicate Glass/Melt”
Date: Oct.5 (wed.) 2016, 13:00-​
Place: Small Meeting Room 1(west), Welfare and Conference Bldg. (C61), Riken, Wako.
​Dr. Toshiaki IITAKA​ (ithes-cond team)

"6th RIKEN-Kyoto U joint workshop for data assimilation"
September 14, 2016 13:30-
Seminar room, RIKEN AICS
http://data-assimilation.riken.jp/jp/events/aics_ku_ws_2016fall/index.html (Japanese only)

This workshop will aim to:
1) promote discussion on data assimilation from mathematical and application points of view.
2) promote collaboration across RIKEN AICS data assimilation research team and Sakajo labo., Kyoto University.
talks will be in Japanese

If you are interested in attending the workshop, please send an email to da-ws-staff@riken.jp by August 28, 2016.
Along with the workshop, there will be K-computer study tour and a social event. Please let us know if you want to join them.

iTHES Data Assimilation School in Kobe
Sep.12 (Mon)-14 (Wed), 2016

This is a school sponsored by iTHES on Data Assimilation for non-experts organized by Dr. Takemasa Miyoshi (AICS and ithes cs-team).  The school will be held in iTHES Kobe office at the IIB building  (http://blog-imgs-73-origin.fc2.com/k/o/b/koberun/medical143.jpg) in Port Island (https://en.wikipedia.org/wiki/Port_Island).

Data assimilation (https://en.wikipedia.org/wiki/Data_assimilation) is a field to combine computer simulations and the real data to make better prediction of the future state of the actual system.  
This time, the school starts with a general introduction to Data Assimilation followed by the practice/training session with the weather forecast as one of the most important examples of  the application of data assimilation.  Feel free to register from the above web page to learn the basics of this exciting interdisciplinary field!

iTHES workshop
"Controlling Complex Network Systems in Biology"
Date: September 5, 2016 (Mon)
Place: 2F Meeting Room in Wako Main Cafeteria, RIKEN Wako
(Welfare and Conference Bldg. C61)

Controlling complex biological systems is one of the most important missions in basic biology and medical science. Especially in regenerative medicine, it is strongly required to establish non-empirical methods to control dynamics of gene expressions and to regenerate cells or tissues artificially. Experimental studies have provided large information on interactions between bio-molecules. However, such network information is not sufficient to specify detail of the dynamics of systems.
In this workshop, we invite advanced researchers studying theoretical methods to control complex network systems. We discuss mathematical and practical aspects of these methods, and consider possible collaborations between different methods. Each speaker has 60min presentation (including discussions).

9:55 - 10:00    Opening remark

10:00 - 11:00   Tatsuya Akutsu (Kyoto University, Japan)
"Minimum Dominating Set-Based Approaches for Controlling and Analyzing Biological Networks"

11:00 - 12:00   Ying-Cheng Lai (Arizona State University, USA)
"Controlling Complex Networks"


13:30 - 14:30   Atsushi Mochizuki (RIKEN, Japan)
"Controlling Complex Systems based on Network Structures"

14:30 - 15:30   Jorge Gómez Tejeda Zañudo (Pennsylvania State University, USA)
"Structure-based control of complex networks with nonlinear dynamics"


16:00 - 17:00   Koichi Kobayashi (Hokkaido University, USA)
"Design of Deterministic/Probabilistic Boolean Networks Based on Partial Knowledge"

17:00 - 18:00   Takashi Okada (RIKEN, Japan)
"Law of Localization in Chemical Reaction Networks"

18:30 - Dinner

"Thermal Quantum Field Theory and Their Applications"
August 22(mon) - 24(wed), 2016
Suzuki Umetaro Hall, Wako campus, RIKEN
http://www.riise.hiroshima-u.ac.jp/TQFT/ (Japanese only)

In this workshop sponsored by iTHES, talks will be in Japanese
Contact person: Yoshimasa Hidaka (iTHES associate, ithes-phys team)

"The 10th APCTP-BLTP/JINR-RCNP-RIKEN Joint Workshop on Nuclear and Hadronic Physics"
August 17(wed) - 21(sun), 2016
Okochi hall,  Wako campus, RIKEN

In this workshop sponsored by iTHES, latest issues in nuclear and hadronic physics will be discussed.  The topics include few-body nuclear systems, cluster dynamics in exotic nuclei, superheavy nuclei, multiquark hadrons, hadrons under extreme conditions, and also related subjects in atomic and molecular physics. Progresses of computational methods in particle and nuclear physics will be also discussed.

Contact person:  Emiko Hiyama (ithes-phys team)

"Developments in supersymmetric field theories"
August 17(wed)-19(fri), 2016
Large conference room on the 2nd floor of the main cafeteria, RIKEN
https://sites.google.com/site/susyithes2016/ (Japanese only)

In this workshop sponsored by iTHES.
Contact person: Masato Taki (ithes -phys team)

iTHES-Osaka-OIST Joint Workshop 2016
"Big Waves of Theoretical Sciences in Okinawa"
July 8 (Fry.) - July 11 (Mon), 2016

This is the 3rd Joint workshop on theoretical science organized by OIST and RIKEN iTHES. The main purpose of this workshop is to promote interactions among researchers from different fields of science and to afford a good opportunity for them to start new collaborations. The workshop is also aimed at helping the participants to deepen their understandings of the fields which they have not been mainly studying, by teaching one another the new developments of their own research fields. This year's main topics are, Machine Learning, Theoretical Biology, Soft Matter Physics and Quantum Physics.  The present workshop is supported by OIST, RIKEN iTHES, and Osaka CTSR. 


Organizers: Masaru Hongo (RIKEN iTHES) Chair, Tomoki Tokuda (OIST), Koji Hashimoto (Osaka)

"14th International Conference : Nuclei in the COSMOS XIV"
19-24, June, 2016
will be held in Niigata, Japan.  
The conference is co-sponsored by iTHES.

The main topics of the conference are
*Big-Bang Cosmology, Nucleosynthesis, Dark Matter, and Dark Energy
*First Generations of Stars and Galactic Chemo-Dynamical Evolution
*Stellar Evolution and Hydrostatic Nuclear Burning Processes
*Explosive Nucleosynthesis in Stars
*Supernovae, Gamma-Ray Bursts and Mergers
*Novae and X-Ray Bursts
*Neutron Stars and Hadron Physics
*Meteoritic Abundances, Interstellar Gas and Dust Astronomy
*X and γ Ray Astronomy and Cosmic Ray Astrophysics
*Neutrino Astrophysics and Weak Process
*Radioactive Nuclei Far From Stability
*Nuclear Theory in Astrophysics
*Nuclear Experiments in Astrophysics
*Nuclear Data and Astrophysics
*New Facilities in Nuclear Astrophysics and Astronomy

Theoretical Biology Seminar/iTHES Seminar
"Dynamics of the Calvin cycle"
Date: June 7 (Tuesday) 15:00-
Place: Room 435, Main Research Building
Speaker: Prof. Alan D. Rendall  (Institute for Mathematics, Johannes Gutenberg University Mainz)

There exist a number of different mathematical models for the Calvin cycle of photosynthesis in the literature. These can be used to address different issues of biological interest. In what way can the system fail under conditions of external stress (overload breakdown) Can the system exist in more than one steady state? A positive answer to the latter question might have implications for biotechnology. Up to now most work on these questions has been based on computer simulations. Here I discuss rigorous mathematical results on the multiplicity and stability of steady states in models of the Calvin cycle consisting of systems of ordinary differential equations including different sets of chemical species and making different assumptions on the kinetics of the reactions involved. I will also describe how the techniques used might be applied to models of other biological systems such as signalling pathways.

iTHES mini-workshop
"Dynamics of Virus Infection"
Date: May 26, 2016, 13:30 - 17:00
Place: Room 435,437 in Main research building, RIKEN Wako

Infection of virus is complex dynamical process includes multiple steps of biological events in host cells, entry, replication and shedding. In addition to standard experimental methods, mathematical modeling is expected to take an important role of giving clear understanding to the complex phenomena. In this workshop, we invite advanced researchers studying virus infections by theoretical and/or experimental methods. We discuss possible collaborations between theory and experiment in this field.

13:30 - 14:20
Dr. Catherine A.A. Beauchemin (Ryerson University)
14:30 - 15:20
Dr. Shingo Iwami (Kyushu University)
15:30 - 16:20
Dr. Yoko Aida (RIKEN)

Theoretical Biology Seminar/iTHES Seminar
"Multistationarity in biochemical reaction network models"
Date: May 11 (Wed) 13:30-
Place: Room 435, Main Research Building
Speaker: Prof. Maya Mincheva (Department of Mathematical Sciences, Northern Illinois University)

Biochemical reaction networks are often modeled by large nonlinear dynamical systems with many unknown parameters, which complicates the numerical studies. The existence of multiple positive equilibria referred to as multistationarity, or a biological switch related to cell decision making, is an important property of biochemical reaction networks. The potential for multistationarity can be initially determined by the structure of a reaction network. We will discuss a graph-theoretic condition for multistationarity which includes the positive cycle condition as a special case. Similar graph-theoretic approach can be applied for reaction-diffusion models for the existence of Turing patterns, and for time delay models for the existence of oscillations.
An algorithm for finding multistationary parameter regions for dissipative biochemical reaction network models with bounded solutions will be presented. Multistationary and unique equilibrium regions are identified by studying the sign of a multivariate polynomial with coefficients consisting of parameters. Specifically a model for double phosphorylation will be analyzed for multistationarity. A simple parameter inequality splits the parameter space into regions where the existence of multistationarity or the uniqueness of an equilibrium is guaranteed. Other models of dissipative reaction networks analyzed for multistationarity using the same algorithm will be discussed as well.

April 28 (Thurs.), 2016

iTHES(RIKEN)-AIMR(Tohoku)-IIS(Tokyo) Joint Symposium:
"New Horizon of Mathematical Sciences"
time: 10am-6pm
place: Suzuki Umetaro Hall at RIKEN Wako campus.

This is a symposium to cerebrate the establishment of the Mathematical Sciences Team in iTHES Research Group at RIKEN.
The symposium is organized jointly with Advanced Institute for Materials Research (AIMR) at Tohoku Univ. and Institute of Industrial Science (IIS) at The Univ. of Tokyo.

At this symposium, researchers from various branches of mathematical sciences are invited, including pure mathematics, applied mathematics, theoretical physics and theoretical biology.
We will also have a keynote lecture and panel discussions to exchange ideas about the future role of mathematics to intertwine different fields and disciplines.

All talks are given in Japanese, while the slides are prepared in English.

Please take a look at the program in the above web page and register as soon as possile from the page.

Tetsuo Hatsuda (RIKEN iTHES)
Motoko Kotani (AIMR, Tohoku Univ.)
Kazuyuki Aihara (IIS, Univ. Tokyo) 
Shigefumi Mori (IAS, Kyoto Univ.)  

--- List of speakers ----

* Keynote lecture:
Reiko Miyaoka (Tohoku Univ.) "Math is Everywhere"

* Invited talks:

Masato Taki (RIKEN  iTHES)
"String theory as an attempt of polymathematics"

Takahiro Omi (IIS, Tokyo)
"Probabilistic aftershock forecasting: A Bayesian statistical approach"

Shinichiroh Matsuo (Nagoya)
"Topological phases and K-theory"

Yuki Yokokura (RIKEN iTHES)
"Thermodynamic entropy as a Noether invariant"

Horoaki Hiraoka (AIMR, Tohoku)
"Topological data analysis in materials science"

Takuya Kanazawa (RIKEN iTHES)
"Renormalization group for physics with multiple scales"

Tomoya Takeuchi (IIS, Tokyo)
"Augmented Lagrangian Methods for Convex Optimization"

Takashi Okada (RIKEN)
"Response-perturbation relation and network topology in chemical reaction systems"

"Highly Frustrated Spin-Lattice Models of Magnetism and Their Quantum Phase Transitions: A Microscopic Treatment via the Coupled Cluster Method"

Date: Apr 7 (Thu) 2016, 13:30-
Place: Small conference room on the 2nd floor of the main cafeteria
Speaker: Raymond Bishop (School of Physics and Astronomy, The University of Manchester)

(please see the attached)

"All-dielectric nanophotonics and metasurfaces"

Date: April 4th (Monday) 2016, 14:00-
Place: Seminar room on top of the large cafeteria (located on the 2nd floor)
Speaker: Prof. Yuri S. Kivshar (Nonlinear Physics Center, Australian National University, Canberra, Australia)

Rapid progress in plasmonics is driven by the ability to enhance near-field effects with subwavelength localization of light. Recently, we observe the emergence of a new branch of nanophotonics aiming at the manipulation of strong optically-induced electric and magnetic Mie-type resonances in dielectric and semiconductor nanostructures with high refractive index. Unique advantages of dielectric resonant optical nanostructures over their metallic counterparts are low dissipative losses, low heating, and the enhancement of both electric and magnetic fields. In this talk, I will review this new emerging field of nanophotonics and metamaterials and demonstrate that Mie-type resonances in dielectric nanoparticles and subwavelength dielectric structures can be exploited for new physics and novel functionalities of photonic structures especially in the nonlinear regime.


Prof. Yuri S. Kivshar

Yuri S. Kivshar received PhD in 1984 in the Ukraine. After working at several research centers he moved to Australia in 1993 where he established Nonlinear Physics Center. Kivshar’s research interests include nonlinear photonics, optical solitons, metamaterials, and more recently nanophotonics. He is Fellow of the Australian Academy of Science, OSA, APS, and IOP. He received many awards including the Pnevmatikos Prize in Nonlinear Science (Greece), Lyle Medal (Australia), State Prize in Science and Technology (Ukraine), and Harrie Massey Medal (UK).

3rd mini-symposium on Computations, Brains and Machine
Date: March 17, 2016, 1:30 pm -
Place: the seminar room, 1F, at BSI Central Building

Brain does amazingly efficient computation over big and complex information, while modern neuroscience itself often requires such computations for analyzing the data, to address mysteries of brain. To gain the insights for uncovering the superb neuro-computational principles and intelligence, the series of this mini-symposium is intended to discuss better computations and greater mathematical principles in a wider perspective, not only in theoretical neuroscience but also in machine learning and statistical-information sciences. This time, four eminent speakers will introduce us to cutting-edge works to face such challenges in their own disciplines. Who knows that these perspectives might be integral for future neuroscience?

13:30-13:35  Opening
13:35-14:20  Dr. Yoshimasa Tsuruoka (The University of Tokyo):
Recent Advances in Natural Language Processing and Game AI
14:20-15:05  Dr. Mahito Sugiyama (Osaka University):
Statistical Analysis on Order Structures
15:30-16:15  Dr. Makoto Yokoo (Kyushu University):
Market Design: Designing Social System by Game Theory
16:15-17:00  Dr. Tetsuya Ogata (Waseda University):
Deep Neural Models for Multimodal Integration in Robot System
17:00-17:45   Informal discussion (at Nakahara Lab/N201) 

iTHES Symposium
Baymfest in Tokyo:
"Exploring Extreme Forms of Matter - A symposium in honor of Professor Gordon Baym -"
Date: March 14 (Mon) 2016. 10:00am-
Place: Faculty of Science 4th-bldg 1320, Department of Physics, The University of Tokyo

This is a joint symposium hosted by The University of Tokyo and RIKEN on nuclear physics, condensed matter physics and astrophysics in hornor of Prof. Gordon Baym's 80th birth year. We welcome participation of all scientists who are interested in these fields and related interdisciplinary research. We hope to have fruitful discussions on the current status and future perspectives in these fields at the symposium.

"LIGO Gravitational Wave Detection Seminar"
Date: March 7 (Mon) 2016 16:00-
Place: BSI Ikenohata Building, 3rd floor, large conference room
Speaker: Prof. Kipp Cannon (RESCEU, The Univ. of Tokyo;  LIGO member) 
Contact: Kazuo Maxima (maxima@phys.s.u-tokyo.ac.jp) 

12th International Conference on Low Energy Antiproton Physics (LEAP2016)
Date: March 6-11, 2016
Place: Kanazawa Japan

The intent of LEAP 2016 is to actively stimulate the overlap and dialogue between various research forefronts in the diversified field of antiproton physics and related field involving meson and baryon with strangeness.
iTHES is a cosponsor of this meeting.
Feel free to join !

“ICA (Independent Component Analysis) and the Big Bang”

Date: March 3(Thursday), 2016, 15:00 – 17:00
Place: 3F S305 seminar room, BSI Central Building
Speaker: Prof. Jean-Francois Cardoso
(Telecom ParisTech/CNRS, University Paris 7, Cosmology)

In 2013, the Planck collaboration from the European Spatial Agency released its first results and products, including a full-sky high-resolution map of the Cosmic Microwave Background (CMB) which made the headlines of newspapers worldwide.  Indeed, that image is quite literally a snapshot of our Universe in its infancy, when it was a promising but fragile baby, only 380.000 years old.  The CMB map is obtained by combining the 9 frequency channels of the Planck satellite in order to separate the precious relic radiation from many other astrophysical emissions.  This is a source separation issue which, as it turned out, was best solved by a blind method -- in other words, by ICA:
Independent Component Analysis-- carefully crafted to deal with the uncertainties in the sky and the wild SNR conditions in the data.
The talk will start with an introduction to Big Bang theory, the standard cosmological model, so beautifully supported by Planck results.  I will then describe the Planck satellite and sketch its data processing pipeline up to the inference of the cosmological parameters.  I will focus on my main contribution to it: blind separation of the CMB from all the other emissions by an ICA algorithm based on a Gaussian spectral likelihood.

Host: Shun-ichi Amari
Lab. for Mathematical Neuroscience (ext. 7142) 

iTHES one-day workshop "Storage Rings and Tests of Fundamental Symmetries" 

Date: Mar. 2 (Wed) 10:00-
Place: room 535 (Main research building)  

Invited speakers are:
Makiko Nio (RIKEN)
Daisuke Nomura (YITP)
Masashi Otani (KEK)
Yannis K. Semertzidis (KAIST/IBS)
Koichiro Shimomura (KEK)
Yasunori Yamazaki (RIKEN) 

For detail, please see
The registration is not needed for the participation to the workshop. 

Date: Feb 19 (Fri)
Time: 14:00-
Place: Large conference room at the 2nd floor in main cafeteria

Speaker: Dr. Chao GAO (Renming University of China)
Title: Universal three-body physics and the link to many-body physics

Abstract: I will introduce to you the exotic universal three-body physics, the Efimov states, that is, three-body bound states with scaling spectrum emerging at two-body resonances. I will then discuss the link between few-body and many-body physics through virial expansion. Specifically I will take the example of unitary Fermi gases, where we shall see the role of the so-called three-body parameter.  I will also introduce to you another kind of universal three-body bound states, the super-Efimov states, which is more peculiar and firstly discovered in two-dimensional systems at p-wave channel. I will discuss its origin at fundamental quantum mechanics level.

Date and Time: 10:30-12:00, Feb. 16 (Tuesday), 2016
Place: S406 Bioscience Building, RIKEN Wako Campus
(Bioscience Building is “S01” in the map)

Speaker: Prof. Catherine Beauchemin (Department of Physics, Ryerson University)
Title: An introduction to the field of virophysics

Experimentation in vitro and in vivo has traditionally been the only way to study virus infections; there is no such thing as theoretical virology. When adopting an experiment-only approach, one must rely on common-sense assumptions to derive knowledge (e.g., a higher viral count means a fitter virus). These assumptions often go untested due to difficulties in controlling individual components of infection without affecting others. In this talk, I will show how mathematical and computer models (MCMs) allow us to better understand cell-virus interactions, and to probe the reproducibility of virology results which is an important problem in health research. I will introduce our MCM for influenza infection in vitro and illustrate its use to determine the effect of a specific mutation (genotype) on every aspect of the virus' replication fitness (phenotype). I will demonstrate the MCMs' ability to find flaws in experiments, and determine antiviral efficacy and optimal combination therapy.

This talk is suitable for mathematicians, physicists, and virologists alike.

Computaional Brain Sciecene WS
Date: Jan.28 (Thu) 13:30-17:40
Place: Seminar room, 4th floor, Brain Science Central Bldg.

iTHES Seminar
Date: Jan.25 (Mon) 15:30-
Place: room 433 (Main research building)
"A mathematical model of molecular mimicry and autoimmune disease"
Prof. K. Tokita (Nagoya Univ.)

Fundamental Physics Using Atoms 2015
- Towards better understanding of our matter universe -

Nov. 30 (Mon.) -- Dec. 1 (Tue.), 2015
Oral sessions: RIKEN Wako, Okochi Hall (C32)
Poster sessions: Welfare and Conference Bldg. 2F (C61)

     Recently much effort has been directed to investigation of the fundamental physics which exploits remarkable developments in atomic physics and/or quantum optics techniques. Examples include (A) test of the time reversal invariance by observing permanent electric dipole moments of atoms or molecules, (B) neutrino mass spectroscopy using atoms, (C) measurement of fine structure constant's time dependence with precession atomic clock etc. This conference aims to bring together recent research results, to discuss future prospects, and to expand research network, making this field more active and productive.

RIKEN Symposium
"Toward the Advanced Integrated Intelligence Research"

Date: November 28 (Sat.) 10:00-17:00
Place: Okochi hall
Y. Nakamura (CEMS), S. Nagataki (iTHES), M. Nikaido (ACCC), J. Makino (AICS), T. Miyoshi (AICS), K. Mochida (CSRS), T. Tsunoda (IMS), T. Toyoizumi (BSI), M. Taiji (QBiC),  K. Takahashi (QBiC)
Language: Japanese
Contact: N. Maeda (norihiro@riken.jp)
Advanced Integrated Intelligence Research Project Preparatory Office

"A couple of recent developments in atomistic simulations of solid and soft(bio) matter"
Boero Mauro (Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), University of Strasbourg and CNRS, UMR 7504, 23 rue du Loess, F-67034, Strasbourg, France Computational Materials Science Initiative (CMSI) at Dept. of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan)
Date:November 26th (Thu.) 10 a.m. 11月26日(木)10:00-
Place:Meeting room  AB, Laser Science Laboratory  理研 和光キャンパス レーザー棟会議室AB

Abstract: A brief overview on recent advanced computational approaches used in the modeling of amorphous materials and biochemical reactions is presented, along with the most recent applications. The scope is to bring attention on advances in DFT-based techniques to extend the time and size scale of the simulations to a more realistic modeling. At the same time, we wish to underscore the still existing limitations in these methodologies. After inspecting the basic algorithms [1-2], we shall focus on their practical applications in two cases. The first one is represented by phase-change materials (PCM) [3] able to perform quick transitions between a crystal and an amorphous phase for next-generation optical supports (blue ray). The second one is a peculiar enzymatic reaction operated by a specific bacteria (arthrobacterium sp. KI72) able to “digest” synthetic fibers such as nylon-6 oligomers, resulting as byproducts in manufacturing industry [4,5].
[1] M. Boero, A. Bouzid, S. Le Roux, B. Ozdamar, C. Massobrio, Molecular Dynamics Simulations of Disordered Materials: From network glasses to phase change memory alloys, pag. 35-55, Springer, Berlin Heidelberg 2015. ISBN: 978-3-319-15674-3
[2] M. Boero and A. Oshiyama, Car-Parrinello Molecular Dynamics in Encyclopedia of Nanotechnology, pag. 1-10, Springer, Berlin Heidelberg 2015. ISBN 978-94-007-6178-0; DOI: 10.1007/978-94-007-6178-0_100946-1
[3] A. Bouzid, S. Gabardi, C. Massobrio, M. Boero, M. Bernasconi, Phys. Rev. B 91, 184201 (2015)
[4] K. Kamiya, T. Baba, M. Boero, T. Matsui, S. Negoro, Y. Shigeta, J. Phys. Chem. Lett. 5, 1210 (2014)
[5] T. Baba, M. Boero, K. Kamiya, H. Ando, S. Negoro, M. Nakano, Y. Shigeta, Phys. Chem. Chem. Phys. 17, 4492 (2015)

#16 Pioneer project seminar

"Precision Tests of Discrete symmetries at Low Energies"
Prof. Klaus Jungmann (University of Groningen)
Date: Nov. 24th (Tuesday) 2015 (10:00-11:00)
Place: Main research building, 5th floor, 535,537
Language: English

Osaka CTSR - Kavli IPMU - RIKEN iTHES International workshop
"Nambu and science frontier"

Date: 17th November (Tue), 2015
Venue: H701 lecture room, Dept. of Physics, Osaka university
Time: 9:30 - 17:30

Invited speakers
  Kenji Fukushima (U. Tokyo)
  Koji Hashimoto (Osaka U)
  Simeon Hellerman (Kavli IPMU)
  Noriyoshi Ishii (Osaka U)
  Kota Masuda (RIKEN iTHES)
  Yu Nakayama (Kavli IPMU / Caltech)
  Toshifumi Noumi (Hong Kong U. of Science and Technology / RIKEN iTHES)
  Kin-ya Oda (Osaka U)
  Noriaki Ogawa (RIKEN iTHES)
  Haruki Watanabe (MIT)
  Tamiaki Yoneya (U. Tokyo, Open Univ. of Japan)

Koji Hashimoto, Kentaro Nagamine (Osaka CTSR)
Tetsuo Hatsuda, Tsukasa Tada, Masato Taki (RIKEN iTHES)
Hitoshi Murayama  (Kavli IPMU)

Purpose of the Workshop:
     In July 2015, we as the physics community were greatly saddened by the news that Prof. Yoichiro Nambu had passed away.  He proposed many of the fundamental concepts that underlie our current understanding in theoretical sciences.  On this occasion, we’d like to discuss the relevance of Nambu’s concepts and how they will be developed in many areas of science, and promote interdisciplinary collaborations among theoretical sciences.  The joint workshop of Osaka CTSR- RIKEN iTHES - Kavli IPMU is a successive series following the symposium held at Kavli IPMU last year.
The topic of the workshop includes:
- Nambu-Goto action for strings, membranes and higher dim. objects
- Nambu-Goldstone theorem and its extensions
- Nambu-Jona-Lasinio model and its generalizations
- Nambu-Bethe-Salpeter equation and nuclear/hadron physics
- Nambu bracket for quantizing membrane and M-theory
- Higgs inflation
- QCD chiral phase transition
- Symmetry breaking in physical biology

Sponsored by
- Core for Theoretical Science Research (CTSR) , Osaka Univ.
- Interdisciplinary Theoretical Science (iTHES) Research Group, RIKEN
- Kavli IPMU, The Univ. of Tokyo

"The helium Efimov trimer and larger bosonic droplets"
Prof. Doerte Blume (Washington State University)
Date: Nov. 12th (Thursday) 2015 (14:00-)
Place: Main research building, 2th floor, 224
Language: English

The quantum mechanical three-body problem has been studied extensively for about a century. The helium atom (two electrons and a nuclues) and the molecular hydrogen ion (two protons and one electron) are textbook examples that illustrate the organization of the periodic table and molecular binding mechanisms, respectively. In 1970 Vitaly Efimov predicted a rather different and counterintuive quantum mechanical three-body binding mechanism that leads to an infinite series of stable three-body states of enormous spatial extents. These Efimov states are predicted to exist for short-range interactions like the van der Waals force between atoms or the strong force between nucleons. When the potential becomes so shallow that the last two-body bound state is at the verge of becoming unbound or is unbound, then three particles stick together to form Efimov states. This talk will review recent theoretical and experimental advances in this field. The observation of the helium trimer (three neutral helium atoms) Efimov  state and extensions of the Efimov scenario to four- and higher-body systems will be discussed.

Detailed information can also be found in

"Gamma-ray burst supernovae: From central engines to cosmological probes"
Dr. Zach Cano(Centre for Astrophysics and Cosmology, Science Institute, University of Iceland)
Date: Oct. 19 2015 (14:00-15:00)
Place: room 248 in the main research build.
     Peculiar stripped-envelope core-collapse supernovae have been seen to occur at the same spatial locations as long-duration gamma-ray bursts (GRBs).  These so-called gamma-ray burst supernovae (GRB-SNe) are bright and energetic, and their spectra indicate that material within in the supernova outflow propagates at tens of thousands of kilometers per second.  The first GRB-SN was observed in 1998, with more than 30 having been observed to date.  Despite this steady increase in sample size, many outstanding questions remain regarding the physical properties of their pre-explosion progenitor stars, as well as the physical processes that power the initial burst of gamma-rays and the accompanying supernova.  In this talk I will present the latest paradigms that describe the main physical processes that occur during a GRB-SN event, and use these to infer properties of their pre-explosion progenitor star and constrain the nature of the central engine that powers the GRB and the supernova.  I will also briefly present some tentative observations of suspected r-proccess transients associated with short-duration GRBs. I will finish the talk with a presentation of how to use GRB-SNe as cosmological probes to determine the Hubble constant in the local universe.

RIKEN Nishina Center - RIKEN iTHES Joint Seminar

Prof. Bikash Sinha   (Variable Energy Cyclotron Centre, India)
Date: Oct. 6 (Tues.) 2015,  15:00-16:30
Place: Nishina Hall
     Over the years India’s scientific enterprise is inevitably moving towards a global perspective. Mega Science, almost by definition is multi disciplinary and multi institutional and of course global.  In India scientific institutions from small and modest enterprises have gone on to build mega science facilities in India as well as participate in mega science facilities across the world.  The evolution of this adventurous journey from the early sixties to now will be traced touching upon the speaker’s personal involvement.

RIKEN Nishina Center - RIKEN  iTHES - RIKEN CEMS joint seminar

"The Chiral Magnetic Effect: from Quark-gluon Plasma to Dirac Semimetals"
Prof. Dima Kharzeev (Stony Brook Univ. and Brookhaven Natonal Lab.)
Date: Sep. 24, 2015.  13:30-15:00
Place: Okochi Hall
     Recently discovered 3D Dirac and Weyl semimetals possess massless chiral quasi-particles,  and are affected by the triangle anomalies. Quantum anomalies can induce novel  non-dissipative transport phenomena in these materials - so-called "chiral magnetic" and "chiral vortical" effects.
     I will discuss the theory of anomalous transport, the experimental evidence from heavy ion collisions at RHIC and LHC, and the recent experimental observation of the chiral magnetic effect in Dirac semimetals.

Joint iTHES - Math. Cooperation Program Symposium

Date: Sep. 2 (Wed.) 10:00am-
Place: Research Organization of  Information and Systems
Program: TBA
Math. Coop. Program:  http://coop-math.ism.ac.jp/

GRB Workshop 2015 at RIKEN

Date: 31st Aug.- 2nd Sep 2015
Place: Suzuki Umetaro Hall
Please join!


"Few-body dynamics of an electron impurity in a superfluid"
Prof. Hossein Sadeghpour(ITAMP, Harvard University, Cambridge, USA)
Date and Time: August 25th, 2015 (Tuesday) from 2:00 p.m.
Place: Main Research Building Seminar room 435-437 (located on the 4th Floor)
     Impurity dynamics is a cornerstone of many-body scattering physics. More recently, the physics of Efimov states and dressed impurities (polarons) in ultracold atomic gases have captured the imagination of practitioners of few- and many-body physics, for their simplicity and controllability. The interactions are decidedly short-range. Here, I will describe the non-equilibrium few-body dynamics in a BEC subject to a single Rydberg excitation is simulated. The interaction is enormous in energy scale and in size. The absorption spectrum of the system with principal quantum number is investigated, leading to formation of oligomeric molecular Rydberg states. The emergence of a shell structure in which ground state atoms arrange themselves in recombinatorial binding in different molecular potential wells is presented.


"Multi-D simulations of Core-Collapse Supernovae"
Dr. Kuo-Chuan Pan (Basel Univ.)
Date and time: Aug. 5 (Wed.), 14:00 - 15:00
Place: room 224-226 in the main research build.

iTHES seminar

"Advanced Mean Field Theory of Restricted Boltzmann Machine"
Haiping Huang and Taro Toyoizumi (RIKEN Brain Science Institute (BSI))
Date and time: August 3, 3pm-
Place:  Main research building, 4th floor, room 433
     Learning in restricted Boltzmann machine is typically hard due to the computation of gradients of log-likelihood function. To describe the network state statistics of the restricted Boltzmann machine, we develop an advanced mean field theory based on the Bethe approximation. Our theory provides an efficient message passing based method that evaluates not only the partition function (free energy) but also its gradients without requiring statistical sampling. The results are compared with those obtained by the computationally expensive sampling based method.
Reference: http://journals.aps.org/pre/abstract/10.1103/PhysRevE.91.050101


"Hypernuclear Spectra within Mean Field and Beyond Mean Field Approach"
Dr. Peter Vesely, a specialist of hypernucleus.
Date and time: July 27, 14:00
Place: room 224 of the main research building
 For detail, please see

 "Symposium on the Present and Future of iTHES" originally planned on June 15 (Mon), 2015
is postponed until Fall or Winter of this year from various constraints.  We will announce the new date as soon as decided.  Thanks for your understanding.
  Tetsuo Hatsuda

Koji Hashimoto (Osaka Univ.)
"How to see internal space"
June 12 (Fri) 11:00-
Main Research bldg. 248
Is internal space a space?
Internal space, namely, the field space on which some global symmetry (such as U(1) group) acts, is called "internal space" but I don't know precisely why it is called so. In this talk I will explore the question and will come to a certain conclusion, using our new result on general effective action of internal moduli space of domain walls.

2nd String Theory in Greater Tokyo
June 9th, 2015, 9:30-16:20
RIKEN, Nishina Hall
We invite the following two speakers:
Michele Del Zotto(Harvard Univ)
Masaki Shigemori(Kyoto Univ)
They will give pedagogical talks about forefront of sting theory.
We also have local and short talk speakers:
Akinori Tanaka (RIKEN)
Tetsuji Kimura (Tokyo Institute of Technology)
Tomoki Nosaka (Kyoto University)
Hironori Mori (Osaka University)
Yoshiki Sato (Kyoto University)
Hiroyuki Shimizu (Tokyo University)
Shotaro Shiba (Kyoto Sangyo University)
Sotaro Sugishita (Kyoto University)

June 4 (Thur.) from 2:00 pm
Dr. William Witczak-Krempa (https://www.perimeterinstitute.ca/people/william-witczak-krempa)
Constraining quantum critical dynamics: 2+1D Ising model & beyond
Rm 154&156, Main Research Building, Wako campus, RIKEN
Quantum critical (QC) phase transitions generally lead to the destruction of quasiparticles. The resulting correlated quantum fluid, when thermally excited, displays rich universal dynamics. We establish non-perturbative constraints on the linear-response dynamics of QC systems at finite temperature, in spatial dimensions above one. Specifically, we analyze the large frequency/momentum asymptotics of observables, which we use to derive powerful sum rules. The general results are applied to the O(N) Wilson-Fisher fixed point (CFT), describing the QC Ising and XY models when N=1,2, respectively. We'll contrast the results with Dirac fermions. Our focus will be on the order parameter susceptibility, conductivity, and shear viscosity. Connections to quantum Monte Carlo simulations, experiments and AdS/CFT will be made.
It's based on my recent paper (http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.177201), and other works with Subir Sachdev.

Dr. Tomoyuki Higuchi
(The Institute of Statistical Mathematics)
"Interaction, Integration, and Design: Key elements for success on promoting the interdisciplinary research"
(in Japanese)
June 4 (Thur.) 2015, 10:30-11:30
Main research building 435-437

Prof.Yasuhiro Masuda (Institute of Particle and Nuclear Studies, KEK)
EDM Measurement with Ultracold Neutrons
Fri 29th May 2015 11:00-12:00
Main research building, 5th floor, 535,537
CP violation is one of important issues in particle physics. The CP violation induces an electric dipole moment in the neutron (nEDM). With nEDM, many theories of particle physics have been tested. Although the standard model predicts very small values of nEDM, new physics such as supersymmetric theory as well as multi-Higgs model, which is beyond the standard model, predicts nEDM values in a 10^{-27} e cm region. The present state of the arts nEDM measurement is at Grenoble, which shows the upper limit of 3×10^{-26} e cm. In this measurement, ultracold neutrons (UCN) was used. UCN are very low energy neutrons, which can be confined in a measurement cell. The precision of the measurement was limited by the number of UCN in the cell, but the improvement of the number of UCN was strongly limited by Liouville’s theorem. Many institutes have been developing super thermal UCN sources, which get rid of this limitation. Here, we discuss our approach to this problem. Our UCN source became world competitive. We also discuss the present status and the future direction of our nEDM measurement.

Kazunori Kohri (KEK)
Close Encounters of the Dark Matter
12:30-13:30, May 29.
Room 535-537 in the Main Research Build.
I review the current status of the dark matter research for non-specialists.

The seminar on 15th May (Fri.)
Shin'ichiro Ando (Assistant Professor, GRAPPA Institute at University of Amsterdam)
Cosmic gamma-ray and neutrino backgrounds: Astrophysical and dark matter implications
Main Research Building, Room 224-226

The seminar on 8th May (Fri.)
Guillaume Lambard (Research Fellow, Institute for Basic Science Daejeon, Republic of Korea)
A novel direct method to the surface density of dark matter in spirals
Main Research Building, Room 433

May 7th (Thursday) from 1:30 p.m.
Dr. Erik Gauger (Institute of Photonics and Quantum Sciences, Heriot-Watt University, UK)
Superabsorption, dark-state protection and optical ratchets: Harnessing collective effects for enhanced light absorption with coupled nanostructures
Main Research Building, room 435-437 (4th floor Seminar room)
I will discuss ring-like structures of optically active quantum nanostructures which interact with a common electromagnetic environment as well as experiencing the influence of their condensed matter host environment. Often considered detrimental, I will argue that the fundamentally present pairwise couplings of such systems can in fact be an asset for unlocking light absorption beyond what is possible classically. Suitably engineered systems may support one or more of several distinct effects contributing to quantum enhanced photon absorption: inverting superradiance, breaking detailed balance, und optical ratcheting. Potential practical applications of these effects include improved photon detectors and light harvesting devices.
1) Nature Communications 5, Article number: 4705 doi:10.1038/ncomms5705 (2014). http://www.nature.com/ncomms/2014/140822/ncomms5705/full/ncomms5705.html.
2) http://arxiv.org/abs/1504.05849

April 30th (Thursday) from 2:00 p.m.
Main Research Building, room 535-537 (5th floor Seminar room)
Mr. Luigi Garziano (Dipartimento Fisica e Scienze della Terra, Messina University, ITALY)
Exploring the USC regime in circuit QED and cavity optomechanics
Recently, due to the experimental progress in the development of circuit QED systems, it is possible to obtain the so called ultra-strong coupling (USC) regime between one or more artificial atoms (qubits) and a superconducting resonator. The USC regime presents indeed a great variety of phenomena that cannot be observed in the conventional weak- and strong-coupling regimes [1,2]. For example, situations may arise where the resonator field acquires a nonzero expectation value in the system ground state. It is possible to demonstrate that, in this case, the parity symmetry of an additional artificial atom with an even potential is broken by the interaction with the resonator [3]. Such a mechanism shares some analogies with the Higgs mechanism where the gauge symmetry of the weak force’s gauge bosons is broken by the nonzero vacuum expectation value of the Higgs field. These results can open the way to controllable experiments on symmetry-breaking mechanisms induced by nonzero vacuum expectation values.
Cavity-optomechanics experiments are also rapidly approaching the USC (or single-photon) regime, where the radiation pressure of a single photon displaces the mechanical resonator by more than its zero-point uncertainty. Ultrastrong interactions in optomechanical systems can be used to force the system ground state to evolve into an arbitrary quantum state of mechanical motion in a completely controlled and deterministic manner. The general strategy for creating such states was first described by Law and Eberly in the context of cavity QED [4] and has been applied to optomechanical systems for the synthesis of arbitrary nonclassical motional states [5] and for engineering arbitrary motional and entangled states of a single trapped ion beyond the Lamb-Dicke limit [6]. In contrast to the Law and Eberly algorithm, a new protocol has been recently proposed in order to synthsesize an arbitrary superposition of N Fock states by applying in single-step N classical optical signals of different frequencies for a common time interval [7]. Since a key requirement for synthesizing arbitrary quantum states is that the preparation time needs to be much shorter than the decoherence time, the proposed scheme provides a promising strategy to fully control the quantum state of massive mechanical oscillators. This scheme can be applied to various strongly interacting quantum systems as trapped ions beyond the Lamb-Dicke regime and cavity QED into the ultrastrong coupling regime. The protocol can also be extended for the generation of entangled states between different mechanical oscillators.
[1] A Ridolfo et al, “Photon blockade in the ultrastrong coupling regime” Phys. Rev. Lett. 109, 193602 (2013)
[2] R Stassi et al, “Spontaneous conversion from virtual to real photons in the ultrastrong-coupling regime”, Phys. Rev. Lett. 110, 243601 (2013)
[3] L Garziano et al, “Vacuum-induced symmetry breaking in a superconducting quantum circuit” , Phys. Rev. A 90, 043817 (2014)
[4] C. K. Law and J. H. Eberly, “Arbitrary Control of a Quantum Electromagnetic Field”, Phys. Rev. Lett. 76, 1055 (1996)
[5] X.-W. Xu, H. Wang, J. Zhang, and Y. X. Liu, “Engineering of nonclassical motional states in optomechanical systems”, Phys. Rev. A 88,063819 (2013)
[6] L. F.Wei,Y.-x. Liu, and F. Nori, “Engineering quantum pure states of a trapped cold ion beyond the Lamb-Dicke limit”, Phys. Rev. A 70, 063801 (2004)
[7] L Garziano et al, “Single-step arbitrary control of mechanical quantum states in ultrastrong optomechanics”, Phys. Rev. A 91, 043817 (2015)

April 28th (Tuesday) from 2:00 p.m.
Main Research Building, room 535-537 (5th floor Seminar room)
Dr. Roberto Stassi (Dipartimento di Fisica e Chimica, Group of Interdisciplinary Theoretical Physics, Università di Palermo and CNISM, Italy)
Quantum vacuum radiation in ultrastrong coupling cavity QED and in stripline waveguides
The dynamical Casimir effect predicts that, when a mirror is shaken into empty space, it emits light. Such a surprising prediction has been confirmed experimentally only recently, when photons emitted out of the vacuum have been observed in a superconducting waveguide [1,2]. Interestingly, the dynamical Casimir effect emits photons in entangled pairs. In this presentation I show how, going beyond the single waveguide paradigm using a scalable array, it is possible to create multipartite nonclassical states, with the possibility to control the long-range quantum correlations of the emitted photons. In particular, our finite-temperature theory shows how maximally entangled NOON states can be engineered in a realistic setup. Moreover, I show that a spontaneous release of virtual photon pairs can occur in a quantum optical system in the ultrastrong coupling regime. In this regime, which is attracting interest both in semiconductor and superconducting systems, the light-matter coupling rate becomes comparable to the bare resonance frequency of photons. In contrast to the dynamical Casimir effect and other pair creation mechanisms, this phenomenon does not require external forces or time dependent parameters in the Hamiltonian [3,4].
[1] J. R. Johansson, G. Johansson, C. M. Wilson and Franco Nori, Dynamical Casimir Effect in a Superconducting Coplanar Waveguide, Phys. Rev. Lett. 103, 147003 (2009), DOI: 10.1103/PhysRevLett.103.147003.
[2] C. M. Wilson, G. Johansson, A. Pourkabirian, M. Simoen, J. R. Johansson, T. Duty, F. Nori & P. Delsing, Observation of the dynamical Casimir effect in a superconducting circuit, Nature 479, 376 (2011), DOI: 10.1038/nature10561.
[3] R. Stassi, A. Ridolfo, O. Di Stefano, M. J. Hartmann, and S. Savasta, Spontaneous Conversion from Virtual to Real Photons in the Ultrastrong-Coupling Regime, Phys. Rev. Lett. 110, 243601 (2013), DOI: 10.1103/PhysRevLett. 110.243601.
[4] L. Garziano, A. Ridolfo, R. Stassi, O. Di Stefano, and S. Savasta, Switching on and off of ultrastrong light-matter interaction: Photon statistics of quantum vacuum radiation, Phys. Rev. A 88, 063829 (2013), DOI: 10.1103/PhysRevA

iTHES Seminar
Speaker: Toshikazu Ebisuzaki (RIKEN Computational Astrophysics Laboratory)
Title: Accretion Disk around a protostar and Planet Formation
Date & Time: 24th April, 14:00-15:00
Place: Room 248, Main Research Building
Language: English

April 15th (Wednesday) from 3:30 p.m.
Main Research Building, room 435-437 (4th floor)
Prof. Salvatore Savasta (Dipartimento di Fisica e di Scienze della Terra, Università di Messina, Messina – Italy)
Bare and Physical Excitations in the Light-Matter Ultrastrong Coupling Regime
I will discuss photon coincidence counting statistics and field-quadratue measurements in the ultrastrong coupling regime, where the atom-cavity coupling rate becomes comparable to the cavity a and/or the atomic resonance frequency (see e.g. [1-3]). In this regime, usual normal order correlation functions fail to describe the output photon statistics. By expressing the electric-field operator in the cavity-emitter dressed basis, it is possible to derive detectable correlation functions that are valid for arbitrary degrees of light-matter interaction [3]. I will show applications to different cavity-QED processes as the photon-blockade [3], thermal emission [4], and squeezing. This theoretical framework evidences a clear distinction between bare unobservable excitations and physical excitations that can be detected [5], in close analogy to processes in quantum field theory. I will discuss preliminary proposals based on coupled arrays of nonlinear resonators to explore these connections.
[1] T. Niemczyk et al., Circuit quantum electrodynamics in the ultrastrong-coupling regime, Nat. Phys. 6, 772 (2010).
[2] S. Gambino et al. , Exploring Light–Matter Interaction Phenomena under Ultrastrong Coupling Regime, ACS Photonics 1, 1042 (2014).
[3] A. Cacciola et al., Ultrastrong Coupling of Plasmons and Excitons in a Nanoshell, ACS Nano 8, 11483 (2014).
[3] A. Ridolfo,M. Leib, S. Savasta, and M. J. Hartmann, Photon Blockade in the Ultrastrong Coupling Regime, Phys. Rev. Lett. 109, 193602 (2012).
[4] A. Ridolfo, S. Savasta, and M.J. Hartmann, Nonclassical Radiation from Thermal Cavities in the Ultrastrong Coupling Regime, Phys. Rev. Lett. 110, 163601 (2013).

April 14th (Tuesday) from 2:00 p.m.
Main Research Building, room 435-437 (4th floor)
Prof. Hui Jing (Department of Physics, HeNan Normal University, China)
Parity-time-symmetric optomechanics
I will talk about our recent works on parity-time (PT) symmetric optomechanics (OM).  This project becomes possible due to two distinct experimental advances, namely, PT-symmetric optics in coupled microresonators (B. Peng, et al. Nature Phys. 10, 394(2014)) and the phonon laser via an OM device (I.S. Grudinin, et al. PRL 104, 083901(2010)). After a brief introduction of the backgrounds and main features of these two experiments, I will show how to hybridize them to control a wide range of OM effects, such as the ultralow-threshold phonon lasing in the PT-symmetric regime, the sudden death of phonon lasing in the PT-breaking regime, the enhanced optical nonlinearity or chaos in the PT-breaking regime, and the spectra-reversed OM-induced transparency, as well as the PT-breaking fast light. The practical applications of PT-symmetric OM or more generally, active OM, in e.g. weak-force sensors are also briefly discussed.

iTHES international workshop
April 7 - 10, 2015
iTHES-NCBS 2nd Joint Meeting on "Theoretical Biology"
web page: http://ncbs-theobio2.riken.jp/
venue: 2nd floor of the main cafeteria ( http://ncbs-theobio2.riken.jp/access/ )
Contact:  A. Mochizuki, ithes-bio team (mochi@riken.jp)
Sponsors:  RIKEN iTHES and Simons Centre at NCBS (http://theory.ncbs.res.in/)

iTHES Seminar

Date: 13:30-, March 24, 2014
Place: S406, Bioscience Building 4F, RIKEN

Speaker: Prof. Matthew Turner (Warwick University - Coventry)
Title: From animal to thermodynamic swarms
Abstract: The controlling interactions in bird flocks, insect swarms and fish shoals are still not well understood. Some authors have proposed interactions that are local in space, either in a metric-based or topological sense. We discuss the evidence for non-local interactions and suggest a natural choice for these that is consistent with the cognitive limitations of a bird's vision. We study this model and the various phenotypes that emerge from it and then present supporting experimental data. Finally, I will study an analogy with thermophoretic colloids that are heated by a focussed external light source. This reveals a previously unidentified connection between animal and thermodynamic swarms.

Speaker: Prof. Pierre Sens (Institut Curie - Paris)
Title: Model of contractile cell motility under confinement.
Abstract: We introduce a simple model of cell motility powered by acto-myosin contraction inside a microchannel. Motion is the result of symmetry breaking in the cytoskeleton, due to an instability of the acto-myosin cortex. Focusing on the limit of high friction or adhesion between the cell and the channel walls, we find that there exist a contractility threshold beyond which the symmetric cell state is unstable and the cell spontaneously starts moving. The threshold depends on the mechanical resistance of the medium inside the channel, and we predict the existence of a bistable state in channels containing highly viscous media, where symmetry breaking and motility need to be activated. If cell motion is opposed by a viscoelastic resistance, an additional oscillatory regime exists where the cell periodically changes directions. Finally, we also study cell penetration inside a viscoelastic medium, which could model a border to a new extracellular matrix or a new tissue. We derive the conditions under which thcell penetrates the medium, is arrested, or bounces against the medium surface, and find that the transition between these different regimes depend in a non-trivial way on controllable parameters such as the channel radius.

March 2(Mon.)-4(Wed.), 2015
RIKEN-Osaka-OIST-Taiwan mathphys workshop
Following our RIKEN-OIST mathphys workshop 2014, this year we will have an enhanced mathphys workshop.
As in the previous series, the workshop participants are invited only, and discussions are encouraged in the relaxing mood of OIST facility.
Room B503, Lab 1, Main Campus,
Okinawa Institute of Science and Technology Graduate University (OIST)
Conformal Field Theory, AdS/CFT, Supersymmetric Gauge Theory, Entanglement, Random Matrix Theory, Quantum Spin Systems, Soliton, Non-equilibrium Systems, etc
Noriaki Ogawa (RIKEN) Chief organizer
Hirohiko Shimada (OIST)
Koji Hashimoto (Osaka u.)
Heng-Yu Chen (National Taiwan u.)

iTHES Seminar
Feb.26 (Thurs.) 13:30-
H. Tsukaya (Univ. Tokyo)
"Unsolved enigmas on mechanisms of unifacial leaf morphogenesis" (in Japanese)
Place: RIKEN Wako Campus, Bioscience building S406

Dr. Imran Mahboob, NTT Basic Research Labs., Kanagawa, Japan
An electromechanical Ising Machine
Friday, February 27, 14:00 -
Main Research Building Seminar room 535-537 (located in the Fifth Floor)
Micro and nanoelectromechanical resonators consisting of a mechanically compliable element embedded in an electrical transduction circuit enable the spectral purity of the mechanics to be exploited for detectors of weak forces, mechanical nonlinearities to be accessed for information processing applications and even the quantum mechanical properties of the mechanics to be studied in a macroscopic framework.
In contrast to these more usual applications, here we push the envelope of the electromechanical resonator platform to develop a simulator to solve intractable mathematical and physical problems. In the first steps to this objective, I will show that all the ingredients necessary to execute the Ising Hamiltonian can be accessed in the electromechanical domain. Specifically, the spin ½ particles of the Ising model are replicated by the phase bi-stability of a mechanical parametric resonance. Multiple parametric resonances then play the role of the spin bath. To create coupling between the mechanical pseudo spins, mechanical two-mode squeezed states are created which can impart correlations between the constituent spins that can replicate a ferromagnetic state. Finally a 2nd order phase transition from a ferromagnetic state to an antiferromagnetic state via a disordered spin state can also be realised by controlling the phase of the non-degenerate parametric down-conversion, used to create the two mode squeezed states, with respect to the constituent mechanical pseudo spins. These results suggest that an electromechanical simulator for the Ising Hamiltonian could be built with not only a large number of mechanical pseudo spins but also with multiple degrees of coupling, a task that would overwhelm a conventional computer.
I. Mahboob, H. Okamoto, K. Onomitsu, and H. Yamaguchi, Two-Mode Thermal-Noise Squeezing in an Electromechanical Resonator, Phys. Rev. Lett. 113, 167203 (2014)

Mini-symposium on "Theoretical Biology"
Feb. 23 (Mon), 13:30-16:45, 2015
13:30-15:00 Prof. Yoh Iwasa (Kyushu University).
"Cultural evolutionary dynamics: illustrated by Hinoeuma superstition in Japan and illegal logging of tropical forests"
15:15-16:45  Prof. Nanako Shigesada (Nara Women’s University)
"Travelling waves of invasive species in periodic patchy environments: effects of diffusion, taxis and population pressure"
Place: Large meeting room in the 2nd floor of the main cafeteria, RIKEN

Feb.3 (Tues.)  14:00-
Place: Suzuki Umetaro Hall, Wako Campus
Speaker: Prof. M. Mimura (Meiji Univ.)
Title: "Transient Self-Organization: Closed Systems vs. Open systems of Reaction and Diffusion"

We will have an iTHES Seminar by Prof. M. Mimura (Meiji Univ.)
He is a mathematician who has been trying to bridge
the phenomena in the real world and mathematics.
Before starting his lecture from 15:00, we will have three short talks
by the ithes researchers.  All the talks are in Japanese this time.

14:00-14:15 M. Taki (ithes-phys)
14:15-14:30 H. Ueda (ithes-cond)
14:30-14:45 Y. Hayakawa (ithes-bio)
14:45-15:00 break
15:00-        Prof. M. Mimura 

The 4th iTHES Academic-Industrial Lecture:
Feb. 2 (Mon) 3pm-5pm
"How Google Translates" (in English)
by Dr. Hideto Kazawa (Google, Senior Engineering Manager)
1. An inside look at Google's Research
2. How Machines Translate
Place: Large conference room, 2nd floor of the RIBF building


Prof. Seiji Miyashita, Department of Physics, Graduate School of Science, the University of Tokyo, Japan
Phase transitions in spin dynamics under time-dependent fields
Thursday, January 29, 15:00-
Main Research Building Seminar room 535-537 (located in the Fifth Floor)
Spin dynamics under time dependent field with and without dissipation effects [1] exhibits various types of phase transitions. We study an ensemble of spins (atoms with a discrete energy states) in a cavity under periodic driving field (AC field):

As a function of photon number a kind of phase transition takes place, i.e., between a region of the vacuum-field Rabi splitting (a hybridization between a cavity (resonator) and cooperative spin systems)[2,3] at low density of light and a region of the standard Rabi oscillation in large density where the light is treated as a classical field. In dissipative environments, we obtained of a phase diagram of the steady states in which a new type of ordered state of driven state appears in a region of strong coupling constant (g) and driving force (ξ) [4]. For the appearance of the new ordered state, the degeneracy of the Floquet qusai-energy (Coherent-Destruction of Tunneling) plays an important role.
We also report a kind of first order phase transition of a uniaxial anisotropic system with large S under a sweeping field, which corresponds to the Stoner-Wohlfarth transition [5], which can be understood from a view point of successive Landau-Zener transitions. This phenomenon corresponds to Landau-Zener transition of the Floquet qusai-eigenstate of the Rabi-oscillation in an AC field. [6].
[1] S. Miyashita: J. of Comp. and Theoretical Nanoscience 8, 919-936, (2011).
[2] I. Chiorescu, N. Groll, S. Bertaina, T. Mori and S. Miyashita: Phys. Rev. B 82, 024413 (1-7) (2010).
[3]S. Miyashita, T. Shirai, T. Mori, H. De Raedt, S. Bertaina, I. Chiorescu: J. Phys. B Atomic Mol. and Opt Phys. 45, 124010 (2012).
[4] T Shirai, T Mori and S Miyashita: J. Phys. B: At. Mol. Opt. Phys. 47, 025501 (2014).
[5] S. Miyashita, B. Barbara and T. Hatomura: in preparation.
[6] K. Hijii and S. Miyashita: Phys. Rev. A 81, 013403 (1-7) (2010).

Jan. 26, 2015 ― Jan. 30, 2015
HPCI-iTHES International Workshop on "Critical Stability in Few-Body Systems",
Place: RIKEN, Wako Campus, Main Research Building, room 435, 437

Jan. 26 (Mon.)
9:50―10:00 E. Hiyama (RIKEN) Opening address
10:00―10:50 Mario Gattobigio (Nice) "Few body universality"
10:50―11:40 Pascal Naidon (RIKEN) "What determines the Efimov three-body parameter?"
11:40―12:30 Hiroya Suno (RIKEN)  "A theoretical study of triatomic helium systems"

Jan. 27 (Tue.)
10:00―10:50 Ludovic Pricoupenko (Univ. Pari6) "Many-bosons in narrow resonances: from 3D to 1D geometry"
10:50―11:40 Naoyuki Sakumichi (RIKEN) "Cluster expansion approach to the BCS-BEC crossover"
11:40―12:30 Rimantas Lazauskas (Strasboug) "Rigorous solution of four-nucleon scattering problem including the breakup"

Jan. 28 (Wed.)
10:00―10:50 Nigel Orr (Caen) "The Heaviest Hydrogen Isotopes: 5,7H"
10:50―11:40 Miguel Marques (Caen) "The Tetraneutron: Past,Present and Future"
11:40―12:30 Jaume Carbonell (Orsay) "Multineutron systems?"

Jan. 29 (Thu.)
10:00―10:50 Didier Beaumel (Orsay) "Some studies of clustering and multineutron systems by missing mass"
10:50―11:40 Valerie Lapoux (Saclay) "The structure and spectroscopy of neutron-rich 6,7,8He isotopes"
11:40―12:30 Keiichi Kisamori (CNS/RIKEN) "Study of tetra-neutron system via exothermic double-charge exchange reaction 4He(8He,8Be)4n"
14:30―15:20 Takashi Nakamura (TIT) "Study of nuclei near and beyond the neutron drip line at SAMURAI at RIBF"
15:20―16:10 Yuki Kubota (CNS/RIKEN) "Probing multi-neutron correlation via knockout reaction"
16:10―17:00 Emiko Hiyama (RIKEN) "Structure of neutron-rich Lambda hypernuclei"

Jan. 30 (Fri.)
10:00―10:50 Jean-Marc Richard (Lyon) "Stability of multiquark systems"
10:50―11:40 Tetsuo Hyodo (YITP) "Structure of near-threshold hadrons"
11:40―12:30 Yoichi Ikeda (RIKEN) "Critical stability in meson-baryon systems"

iTHES Joint International Workshop
"Study of Neuron and Cortex”
Date: Dec. 26, 2014 – Dec. 30, 2014
3rd floor of Frontier Research Laboratory (Area F-5, building No.15 in the map)
E. Hayama(RIKEN), T. Kajii(NAOJ), Y. Funakawa(RIKEN), T. Hatada(RIKEN)

Dec. 22 (Mon) 12:15 -
"Magnetic discrete gauge field in the confining vacua and the supersymmetric index"
Prof. Yuji Tachikawa* (University of Tokyo)
Place: Main Research bldg. 433

Abstract: It has recently been argued that the confining vacua of Yang-Mills theory in the far infrared
can have topological degrees of freedom given by magnetic Zq gauge field,
both in the non-supersymmetric case and in the N=1 supersymmetric case.
In this short note we give another piece of evidence by computing and matching
the supersymmetric index of the pure super Yang-Mills theory both in the ultraviolet and in the infrared.

* Yuji Tachikawa received Hermann Weyl Prize 2014:  http://www.ipmu.jp/node/1933

Prof. Ting Yu, Department of Physics and Engineering Physics, Stevens Institute of Technology, New Jersey, USA
Crossover Between Mon-Markovian and Markov Dynamics Induced by a Structured Environment
Friday, December 19, 10:30-
Main Research Building Seminar room 535-537 (located in the Fifth Floor)
In this talk I will report our recent work on the crossover between non-Markovian and Markov dynamics induced by a hierarchical environment. It is known that non-Markovian evolution of an open quantum system can be induced by the memory effects of a reservoir. Although a reservoir with stronger memory effects may seem like it should cause stronger non-Markovian effects on the system of interest, this seemingly intuitive thinking may not always be correct. We illustrate this by investigating a qubit (a two-level atom) that is coupled to a hierarchical environment, which contains a single-mode cavity and a reservoir consisting of infinite numbers of modes. We show how the non-Markovian character of the system is influenced by the coupling strength between the qubit and cavity and the correlation time of the reservoir.
In particular, we found a new phenomenon whereby the qubit Markovian and non-Markovian transition exhibits a anomalous pattern in a parameter space depicted by the coupling strength and the correlation time of the reservoir.

iTHES Special Lecture:
"Frontiers of Numerical Simulations in Manufacturing Technologies and the Role of Academic-Industrial Collaborations" (in Japanese)
Date: December 18 (Thu) 3pm-5pm
Place:  Large confernce room, 2nd floor of the main cafeteria
Lecturer: Dr. Takashi Ikeda (ASTOM R&D, http://www.astom.co.jp/ )

iTHES Seminar
"The kernel polynomial method and its applications"
Prof. Alexander Weisse (Max Planck Institute for Mathematics, Bonn, Germany)
Date: Dec. 15, 2014, 11:00 - 12:00
Place: Main research building, 224 & 226
Abstract: Efficient and stable algorithms for the calculation of spectral quantities and correlation functions are some of the key tools in computational condensed-matter physics. I will give a short review of algorithms based on Chebyshev expansion and of the kernel polynomial method, which usually scale linearly with the problem dimension. The capacity of these methods will be illustrated with examples from the fields of disordered systems (densities of states, conductivities), electron-phonon systems, or quantum spin models (finite-temperature correlations). In addition, I will show how the kernel polynomial method can be embedded into other numerical techniques, e.g., Monte Carlo simulations.

Prof. Francesco Tafuri, Seconda Università di Napoli & CNR-SPIN, Unità di Napoli ITALY
Frontiers Problems of the Josephson Effect: from macroscopic quantum phenomena decay to nano domain encoding in unconventional junctions and nanostructures
Friday, December 5, 10:15-
Main Research Building Seminar room 435-437 (located in the Fourth Floor)
I will briefly review some general problems of superconductivity through the study of the Josephson effect, which has been in the last 50 years a continuous source of inspiration and progress in different fields. The intrinsic and robust macroscopic quantum coherence of the Josephon junctions is also the basis of well-established applications such as the superconducting quantum interference devices, and of prospective hybrid architecture for quantum information.
I will focus on macroscopic quantum phenomena and nanoscale effects of different types of junctions, including those employing high critical temperature superconductors (HTS). HTS oxides enlarge the occurrence of superconductivity to unexpected energy and length scales, and can be considered as representative at the same time of a wide class of materials characterized by ‘exotic’ superconductivity and of strongly correlated systems.
By investigating escape dynamics, we extract the quantum signature of a junction encrypted in macroscopic quantum phenomena. The moderately damped regime gives new opportunities to explore novel aspects on the interplay between coherence and dissipation, of interest for various quantum hybrid architectures. Dualism and coexistence of nano domain encoding and collective long-range order in escape dynamics of Josephson junctions and nanostructures are finally discussed. These notions should apply to all JJs and all weakly coupled Bose condensate systems.
Results encourage the integration of HTS nanostructures in hybrid systems functional to various applications, and the procedures might be of reference for most junctions composed of unconventional superconductors. In nano-devices standard issues of coherence might be subtly combined with the still unknown nature of HTS.

Dr. Fernando Gonzalez-Zalba, Hitachi Cambridge Laboratory, UK
Probing the limits of gate-based charge sensing
Monday, December 1, 2014, 14:00 - 15:00
Main Research Building Seminar room 435-437 (located in the Fourth Floor)
Quantum computation requires a qubit-specific measurement capability to readout the final state of individual qubits. In the promising solid-state approaches based on superconducting and semiconducting nano-devices experiments are increasing in complexity and it becomes important to simplify the circuit layout and decrease the number of components. One of the components of solid-state quantum computers are the qubit readout electrometers. They are made redundant by the introduction of in-situ gate sensors based on a resonant readout. This technique couples the gate to a resonant circuit and probes the qubit's radio-frequency polarisability. Here, we investigate the ultimate performance of such resonant readout schemes and the noise sources that limit their operation.
We find a charge sensitivity of 37~ue/sqrt{Hz}, the best value reported for this technique, using the example of a gate-sensor strongly coupled to a double quantum dot at the corner states of a silicon nanowire transistor.
We model the charge and phase noise by solving the dynamical master equation of the fast-driven electronic transitions and determine the limits of charge and phase sensitivity of resonant readout. We find comparable performance to standard charge sensors and our model predicts limits of order ne/sqrt{Hz} and urad/sqrt{Hz}. We discuss the experimental factors limiting gate detection and highlight ways to optimise its sensitivity. In total, resonant gate-based detection has advantages over external electrometers not only in terms of reduced number of circuit elements, but also in terms of absolute charge sensitivity.

iTHES Seminar
Date: Nov 17 (Mon) 13:30 -
Place: Main Research bldg. 433
Speaker: Sahin Kaya Ozdemir (Washington U., St. Louis)
Title: Controlling light at the exceptional points with whispering gallery micro resonators

iTHES-IPMU-Osaka Joint Symposium
Nov. 6 (Thu.) 2014 at Kavli IPMU, Univ. Tokyo (http://www.ipmu.jp/ )

If you plan to attend, please register as soon as possible from


The registration will be closed on Oct. 30. (No registration fee.) 
Invited speakers: 
H. Ooguri (IPMU/Caltech)
H. Murayama (IPMU/Berkeley) 
E. Komatsu (Max-Planck-Institut für Astrophysik)
F. Nori (iTHES/CEMS)
Y. Sugita (iTHES/AICS)
K. Fujimoto (Osaka)

iTHES mini workshop on Cloaking, Photonic Lattice & Metamaterial
13:30~17:30, April 14(Mon.), 2014
Main Research Building 4F, Seminar Room 435-437
13:30-14:20 Masato Taki
Asymmetric cloaking, effective Lorentz force and photonic resonator lattice
14:30-15:20 Tomohiro Amemiya
15:20-15:40 coffee break
15:40-16:30 Takuo Tanaka
Towards Three-dimensional Optical Metamaterials
16:40-17:30 Tomoki Ozawa
Berry curvature and quantum Hall effects in photonic lattices

Dr. Zhou Li, Department of Physics, McMaster University, Canada
Modified Dirac fermions in valleytronic materials and topological insulators
Friday, March 28, 10:30-11:30
Main Research Building Seminar room 435-437 (located in the Fourth Floor)
In this talk I will investigate various spin-orbit interactions. As is well known, Rashba spin-orbit interaction is the key for spintronics. In Graphene and topological insulators, the Hamiltonian is similar but with the strength of spin orbit interaction to be at least 100 times bigger, making the system cross over from Schrodinger fermions to Dirac fermions. Other kind of spin-orbit interaction exists in Graphene and Graphene-like materials, for example, the Haldane spin orbit interaction, which plays an important role in spin-valley coupled systems typical for valleytronics. Other Hamiltonian (e.g. warping) and the transport properties (optical and magneto-optical, for example) will be discussed. Finally the impact of electron-phonon interaction on these systems will be addressed.
Reference: [1] Zhou Li and J. P. Carbotte, Phys. Rev. B 87, 155416 (2013). [2] Zhou Li and J. P. Carbotte, Phys. Rev. B 88, 045414 (2013). [3] Zhou Li and J. P. Carbotte, Phys. Rev. B 88, 045417 (2013). [4] Zhou Li and J. P. Carbotte, Phys. Rev. B 88, 195133 (2013). [5] Zhou Li, F. Marsiglio and J. P. Carbotte, Scientific Reports 3, 02828 (2013). [6] Zhou Li and J. P. Carbotte, Phys. Rev. B 86, 205425 (2012).