Introduction to spin-boson model

June 22 (Fri) at 10:30 - 17:30, 2018

Takeo Kato (The Institute for Solid State Physics (ISSP), The University of Tokyo)

10:30-12:30 Introduction to spin-boson model @DR3 (14th Building 213) 14:00-15:30 Kondo effect @DR7 (14th Building 217) 16:00-17:30 Detail of NIBA formalism @DR7 (14th Building 217)

Venue: Yagami Campus, Keio University

Event Official Language: Japanese

Theory of Operator Algebras (2nd)

June 21 (Thu) at 15:30 - 17:00, 2018

Yosuke Kubota (Research Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS))

Please note that the date and time of the 2nd lecture has been changed from May 21 10:30 to June 21 15:30.

Venue: Seminar Room #160

Event Official Language: English

Introduction to Public-Key Cryptography (5th)

June 21 (Thu) at 10:30 - 12:00, 2018

Eren Mehmet Kıral (Visiting Researcher, RIKEN Center for Advanced Intelligence Project (AIP))

Venue: Seminar Room #160

Event Official Language: English

Relative and equivariant Lagrangian Floer homology and Atiyah-Floer conjecture

June 19 (Tue) at 14:30 - 16:00, 2018

Kenji Fukaya (Senior Visiting Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) / Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)

Atiyah-Floer conjecture concerns a relationship between Floer homology in Gauge theory and Lagrangian Floer homology. One of its difficulty is that the symplectic manifold on which we consider Lagrangian Floer homology is in general singular. In this talk I will explain that, by using relative and equivariant version of Lagrangian Floer homology, we can resolve this problem and can at least state the conjecture as rigorous mathematical conjecture. Supported by RIKEN iTHEMS and Tuesday Seminar on Topology (Graduate School of Mathematical Sciences, The University of Tokyo).

Venue: Room 056, Graduate School of Mathematical Sciences, The University of Tokyo

Event Official Language: Japanese

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

June 8 (Fri) at 13:30 - 17:00, 2018

Yuta Kikuchi (RBRC Researcher, Theory Group, RIKEN BNL Research Center, RIKEN Nishina Center for Accelerator-Based Science (RNC))

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

Venue: SUURI-COOL (Kyoto)

Event Official Language: Japanese

On the interplay between intrinsic and extrinsic instabilities of spatially localized patterns

June 7 (Thu) at 15:00 - 16:30, 2018

Yasumasa Nishiura (Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

Spatially localized dissipative structures are observed in various fields, such as neural signaling, chemical reactions, discharge patterns, granular materials, vegetated landscapes, binary convection and block copolymer nanoparticles. These patterns are much simpler than single living cells, however they seem to inherit several characteristic “living state” features, such as generation of new patterns, self-replication, switching to new dynamics via collisions and adaptive morphological changes to environments. These behaviors stem from an interplay between the intrinsic instability of each localized pattern and the strength of external signals. To understand such an interplay, we explore the global geometric interrelation amongst all relevant solution branches of a corresponding system with approximate unfolding parameters. For instance, it has been uncovered that large deformation via strong collision is mapped into the network of unstable patterns in infinite dimensional space, and that an organizing center for 1D pulse generators is a double homoclinicity of butterfly type. Large deformation of patterns is unavoidable so that a global geometric structure formed by all relevant solution branches gives us much more insight rather than conventional PDE approaches. We illustrate the impact of this approach for the case of pulse generators. We also report on the recent exciting finding, namely the formation of exotic 3D nanoparticles of block copolymers caused by the interplay between internal repulsion and affinity to external solvent, which is consistent with experimental results.

Venue: Nishina Hall

Broadcast:#305-2, Computational Science Research Building / SUURI-COOL (Kyoto)

Event Official Language: English

Introduction to Public-Key Cryptography Lecture 4: RZSA encryption

June 7 (Thu) at 10:30 - 12:00, 2018

Eren Mehmet Kıral (Visiting Researcher, RIKEN Center for Advanced Intelligence Project (AIP))

Venue: Seminar Room #160

Event Official Language: English

iTHEMS Science Outreach Workshop 2018

June 1 (Fri) - 4 (Mon), 2018

This is a workshop in which researchers in natural and mathematical sciences and the science journalists get together and discuss outreach activities. iTHEMS started to support this annual workshop as well as the journalist in residence program from last year to establish better science communication. Contact: Takashi Tsuboi (iTHEMS Deputy Director)

Venue: Tambara Institute of Mathematical Sciences, The University of Tokyo

Event Official Language: Japanese

Introduction to Public-Key Cryptography (3rd)

May 24 (Thu) at 10:30 - 12:00, 2018

Eren Mehmet Kıral (Visiting Researcher, RIKEN Center for Advanced Intelligence Project (AIP))

This is a series of lectures "Introduction to Public-Key Cryptography" for non-experts. It will be held twice a month (every other Thursday, about 15 times in total).

Venue: Seminar Room #160

Event Official Language: English

Nerd Nite Tokyo

May 11 (Fri) at 20:00 - 22:00, 2018

Catherine Beauchemin (Senior Visiting Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) / Professor, Department of Physics, Ryerson University, Canada)

Nerd Nite is "the Discovery Channel with beer", a worldwide monthly event series that mixes presentations, performances, trivia, demos, music, and of course drinking. Nerd Nite Tokyo events are held in English. This time, Dr. Catherine Beauchemin (iTHEMS senior visiting scientist) will give a 20min. talk on the problems of being a physicist in the world of virology. Fee: 1000 JPY per person

Venue: Nagatacho GRID (2-5-3 Hirakawa-cho, Chiyoda-ku, Tokyo 102-0093)

Event Official Language: English

Theory of Operator Algebras (1st)

May 10 (Thu) at 15:30 - 16:30, 2018

Yosuke Kubota (Research Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS))

Venue: Seminar Room #160

Event Official Language: English

Introduction to Public-Key Cryptography (2nd)

May 10 (Thu) at 10:30 - 12:00, 2018

Eren Mehmet Kıral (Visiting Researcher, RIKEN Center for Advanced Intelligence Project (AIP))

This is a series of lectures "Introduction to Public-Key Cryptography" for non-experts. It will be held twice a month (every other Thursday, about 15 times in total).

Venue: Seminar Room #160

Event Official Language: English

The 4th MACS Colloquium

April 27 (Fri) at 15:00 - 16:45, 2018

Yuji Tachikawa (Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo)

15:00- Teatime 15:15- Talk by Prof. Yuji Tachikawa 16:45- MACS Student Conference FY2018 The 4th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako by Skype, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good cakes/cookies at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Broadcast:#433, Main Research Building

Event Official Language: Japanese

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

April 27 (Fri) at 14:30 - 17:30, 2018

Aron Beekman (Keio University)

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

Venue: Seminar Room #160

Event Official Language: English

Introduction to Public-Key Cryptography (1st)

April 26 (Thu) at 10:00 - 11:30, 2018

Eren Mehmet Kıral (Visiting Researcher, RIKEN Center for Advanced Intelligence Project (AIP))

A new series of lectures "Introduction to Public-Key Cryptography" (lecturer: Dr. Eren Mehmet Kıral) will be started on April as one of math lecture series. It will be held twice a month (every other Thursday, about 15 times in total).

Venue: Seminar Room #160

Event Official Language: English

Thermodynamic of a one-dimensional Bose gas at low temperature & superfluidity in neutron-star matter

April 24 (Tue) at 15:30 - 16:30, 2018

Giulia De Rosi (The Institute of Photonic Sciences, Barcelona, Spain)

Ultracold atomic gases and neutron-star matter play a paramount importance in many-body physics, by exhibiting important analogies and differences. One of the most interesting phenomena shared by both systems is provided by superfluidity. In the first part of the talk, I will show that the chemical potential of a one-dimensional (1D) interacting Bose gas exhibits a non-monotonic temperature dependence which is peculiar of superfluids. The effect is a direct consequence of the phononic nature of the excitation spectrum at large wavelengths exhibited by 1D Bose gases. For low temperatures T, I demonstrate that the coefficient in the $T^2$ expansion of the chemical potential is defined by the zero-temperature density dependence of the sound velocity and it has been calculated along the crossover between the Bogoliubov weakly-interacting gas and the Tonks-Girardeau gas of impenetrable bosons. The theoretical predictions along the crossover are confirmed by comparison with the exactly solvable Yang-Yang model in which the finite-temperature equation of state is obtained numerically by solving Bethe-ansatz equations. In the second part of the talk, I will show the results of a study of the superfluid gap in pure neutron matter, associated with the formation of Cooper pairs in the $^1S_0$ channel. The interaction responsible of the onset of superfluidity is an effective interaction coming from a nuclear Hamiltonian strongly constrained by phenomenology and obtained from the correlated basis function (CBF) perturbation theory and the formalism of cluster expansions. The calculations have been carried out using an improved version of the CBF effective interaction, in which three-nucleon forces are taken into account using a microscopic model. Our results show that the superfluid transition occurs at values of densities corresponding to the neutron-star inner crust.

Venue: Seminar Room #160

Event Official Language: English

The Description of Biological Phenomena as Open System / Every Biological Variable has a Different Dynamic Range

April 23 (Mon) at 15:00 - 16:30, 2018

Kazuhiro Sakurada (Deputy Program Director, Medical Sciences Innovation Hub Program, RIKEN Cluster for Science, Technology and Innovation Hub (RCSTI))
Jun Seita (Unit Leader, AI based Healthcare and Medical Data Analysis Standardization Unit, RIKEN Cluster for Science, Technology and Innovation Hub (RCSTI))

The Description of Biological Phenomena as Open System / Dr. Sakurada Every Biological Variable has a Different Dynamic Range / Dr. Seita

Venue: Okochi Hall

Broadcast:6F auditorium, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: English

Numerical analysis of point vortex dynamics by the method of fundamental solutions

April 17 (Tue) at 16:00 - 17:30, 2018

Koya Sakakibara (Program-Specific Assistant Professor, Graduate School of Science, Kyoto University)

iTHEMS / KUAMS Joint Seminar

Venue: Maskawa Hall, 1F, Maskawa Building for Education and Research

Event Official Language: Japanese

Including an ocean mixing model in atmospheric data assimilation: a case of Typhoon Soudelor 2015

April 17 (Tue) at 15:00 - 15:30, 2018

Kohei Takatama (Postdoctoral Researcher, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS))

Venue: Maskawa Hall, 1F, Maskawa Building for Education and Research

Event Official Language: English