# Event Schedule

## Events for the 3rd week of April 2021

2021-04-09

The iTHEMS Colloquium and three iTHEMS seminars are scheduled for next week (red). If you are interested, you can also attend the other seminars (blue). And don't forget about the iTHEMS Starter Meeting today! (April 9, 12:30-)

Tuesday, April 13, 16:00- Math-Phys Joint Seminar

Wednesday, April 14, 17:00- Quantum Matter Seminar

Thursday, April 15, 10:00- iTHEMS Biology Seminar (TBD)

Friday, April 16, 13:30- iTHEMS Colloquium

# Award

## Tomoki Ozawa and Hidetoshi Nishimori received the FY2021 MEXT Commendation for Science and Technology

2021-04-08

The Ministry of Education, Culture, Sports, Science and Technology (MEXT) announced the recipients of the FY2021 Commendation for Science and Technology.

Our colleague Tomoki Ozawa (Associate Prof. at AIMR in Tohoku Univ. and iTHEMS visiting scientist) received "Commendation for Science and Technology: the Young Scientists' Award" in recognition of his outstanding research achievements in the theoretical studies of topological physics in atomic and photonic systems.

Our colleague Hidetoshi Nishimori (Specially Appointed Professor, Tokyo Institute of Technology, and iTHEMS senior visiting scientist) received "Commendation for Science and Technology: Prize for Science and Technology" in recognition of his outstanding research achievements in developing the fundamental theory of quantum annealing.

# Seminar Report

## Math Seminar by Dr. Wataru Kai on March 22, 2021

2021-04-05

On March 22, the last iTHEMS Math seminar in FY 2020 was held. This time, we invited Wataru Kai from Tohoku University.

The title of the talk was “The Green-Tao theorem for number fields”. The main topic of the talk was his recent joint work with his collaborators about the Green-Tao theorem and its generalization.

In the first part, he explained the historical background and the technology behind the proof of the Green-Tao theorem, which asserts that there are arbitrarily long arithmetic progressions of prime numbers. In the second part, he introduced algebraic numbers and algebraic integers, which generalize rational numbers and integers, respectively, and he explained how we can generalize the Green-Tao theorem to this situation. For example, if we think of numbers of the form a+b\sqrt{5}, these are algebraic numbers. Plotting them on the ab-plane, each of the numbers corresponds to a lattice point. We can draw a “shape” by choosing finite number of those lattices. Then, the generalized Green-Tao theorem asserts that, by applying scaling and parallel translation, we can make all of the chosen lattice points correspond to prime elements simultaneously. Here, prime element is a generalization of prime number in the world of algebraic numbers. He also explained that at some point of the proof of the generalized Green-Tao theorem, a classical technique well-known to algebraic number theorists plays a fundamental role.

Reported by Hiroyasu Miyazaki

The Green-Tao theorem for number fields

March 22 at 16:00 - 18:10, 2021

# Upcoming Events

## Seminar

### Self-adjoint extension in quantum mechanics and non-Rydberg spectra of one-dimensional hydrogen atom

April 13 at 16:00 - 18:10, 2021

Prof. Takuju Zen (Professor, School of Environmental Science and Engineering, Kochi University of Technology)

We offer a beginner’s guide to the functional-analytical techniques in quantum mechanics, and cover its application to the 1D Coulomb problem. It is shown that the wave function at the diverging point of the Coulomb potential is mathematically described by three-parameter family of generalized connection conditions. A scheme is devised to physically implement the generalized conditions, which provides the way to experimentally realize non-Rydberg spectra in 1D Hydrogen atom.

Schedule:

Part 1, Self-adjoint extension of Hilbert space operator

Part 2, 1D Coulomb problem

Venue: via Zoom

Event Official Language: English

## Seminar

### What "Holography" is and how to use it

April 14 at 17:00 - 18:15, 2021

Dr. Mario Flory (Instituto de Fisica Teorica, Universidad Autonoma de Madrid, Spain)

In this talk, I will give an introduction to the holographic principle and the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence. I will also discuss the role that quantum entanglement plays in this correspondence via the Ryu-Takayanagi formula which maps the calculation of entanglement entropy to a geometric problem of extremal surfaces. Then, I will present a holographic model of a Kondo like effect as an example of how the AdS/CFT correspondence can be employed in practice.

*Detailed information about the seminar refer to the email.

Venue: via Zoom

Event Official Language: English

## Colloquium

### Mirror symmetry and KAM theory

April 16 at 13:30 - 15:00, 2021

Prof. Kenji Fukaya (Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)

13:30pm-15:00pm (JST)

Mirror symmetry is a phenomenon discovered in String theory and is much discussed recently in mathematics especially in the field of complex (algebraic) geometry and symplectic geometry. Strominger-Yau-Zaslow found that this phenomenon is closed related to a Lagrangian torus fibration. In an integrable system in Hamiltonian dynamics, the phase space is foliated by Lagrangian tori. I would like to explain a program that the Lagrangian torus fibration found by Strominger-Yau-Zaslow could be regarded as one appearing certain integrable system and KAM theory (which describes a amiltonian dynamics that is a perturbation of an integrable system) could appear in the situation of Mirror symmetry.

Venue: via Zoom

Event Official Language: English

## Special Lecture

### iTHEMS x academist online open to the public "Mathematical Science World 2021"

April 18 at 10:00 - 16:30, 2021

Dr. Kanato Goto (Special Postdoctoral Researcher, iTHEMS)

Dr. Jeffrey Fawcett (Senior Research Scientist, iTHEMS)

Dr. Takuya Sugiura (Postdoctoral Researcher, iTHEMS)

Dr. Naomi Tsuji (Postdoctoral Researcher, iTHEMS)

Dr. Keita Mikami (Research Scientist, iTHEMS)

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)

Venue: via Zoom

Event Official Language: Japanese

## Colloquium

### The 15th MACS Colloquium

April 23 at 15:00 - 17:30, 2021

Prof. Hiroshi Ishikawa (Professor, Faculty of Science and Engineering, Waseda University)

15:00- Talk by Prof. Hiroshi Ishikawa

16:05- MACS Student Conference FY2021

Venue: via Zoom

Event Official Language: Japanese

## Seminar

### Thermodynamic Uncertainty Relation Connects Physics, Information Science, and Biology

April 28 at 13:30 - 16:00, 2021

Prof. Yoshihiko Hasegawa (Associate Professor, Department of Information and Communication Engineering, The University of Tokyo)

Higher precision demands more resources. Although this fact is widely accepted, it has only recently been theoretically proved. The thermodynamic uncertainty relation serves as a theoretical basis for this notion, and it states that current fluctuations are bounded from below by thermodynamic costs, such as entropy production and dynamical activity. In this seminar, I show a strong connection between the thermodynamic uncertainty relation and information theory by deriving it through information inequality known as a Cramér-Rao bound, which provides the error bound for any statistical estimator. Moreover, by using a quantum Cramér-Rao bound, I derive a quantum extension of thermodynamic uncertainty relation, which holds for general open quantum systems. The thermodynamic uncertainty relation predicts the fundamental limit of biomolecular processes, and thus it can be applied to infer the entropy production, corresponding to the consumption of adenosine triphosphate, of biological systems in the absence of detailed knowledge about them.

*Detailed information about the seminar refer to the email.

Venue: via Zoom

Event Official Language: English

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