Volume 223

iTHEMS Weekly News Letter

Hot Topic

Tetsuo Hatsuda thumbnail

Science Agora 2022 is held November 4-6, 2022

2022-11-04

Science Agora 2022 is held online and in person in the period Nov. 4-6, 2022. There will be many fun sessions that you can join in person or online. There are English sessions too. RIKEN will have a session "Envisioning Futures: Navigating the research landscape with senior women researchers" in which Tetsuo Hatsuda from iTHEMS is one of the speakers.
Enjoy !

Upcoming Events

Seminar

iTHEMS Theoretical Physics Seminar

Tensor renormalization group approach to quantum fields on a lattice

November 8 (Tue) at 13:30 - 15:00, 2022

Shinichiro Akiyama (Specially Appointed Assistant Professor, Quantum Software Project, The University of Tokyo)

Tensor renormalization group (TRG) approach is a variant of the real-space renormalization group to evaluate the path integral defined on the thermodynamic lattice, without resorting to any probabilistic interpretation for the given Boltzmann weight. Moreover, since the TRG can directly deal with the Grassmann variables, this approach can be formulated in the same manner for the systems with bosons, fermions, or both. These advantages of the TRG approach have been confirmed by the earlier studies of various lattice theories, which suggest that the TRG enables us to investigate the parameter regimes where it is difficult to access with the standard stochastic numerical methods, such as the Monte Carlo simulation. In this talk, explaining our recent applications of the TRG approach to several lattice models, we demonstrate the efficiency of the TRG as a tool to investigate lattice theories particularly in higher dimensions and future perspective.

Venue: Hybrid Format (Common Room 246-248 and Zoom)

Event Official Language: English

Lecture

An Introduction to Quantum Measurement Theory for Physicists

November 10 (Thu) - 12 (Sat), 2022

Masahiro Hotta (Assistant Professor, Department of Physics, Graduate School of Science, Tohoku University)

In this lecture, basic concepts in quantum measurement theory are introduced, including measurement operators and POVM's. The related topics are also picked up.

Lecture 1: Nov. 10, 10:30 - 12:00
Lecture 2: Nov. 10, 13:30 - 15:00
Lecture 3: Nov. 10, 15:30 - 17:00
Lecture 4: Nov. 11, 10:30 - 12:00
Lecture 5: Nov. 11, 13:30 - 15:00
Lecture 6: Nov. 12, 10:30 - 12:00

Venue: #345-347, 3F, Main Research Building, RIKEN / via Zoom

Event Official Language: English

Seminar

iTHEMS Biology Seminar

Sociogenesis: motivations and first steps

November 10 (Thu) at 16:00 - 17:00, 2022

Cédric Ho Thanh (Postdoctoral Researcher, Prediction Science Laboratory, RIKEN Cluster for Pioneering Research (CPR))

Sociogenesis is a project that aims to study emergent social behaviors of multi-agent systems. In its simplest form, and agent simply seeks to survive by consuming food and maximizing some happiness score. In this presentation, I will discuss some motivations and inspirations of this project, as well as the challenges to get an agent to survive on its own. I will then showcase some methods to evaluate the quality of agents and their underlying architecture beyond simply looking at their lifespan. I will then conclude with some potential applications. No prior knowledge in reinforcement/deep learning is required to attend this presentation. This work is still mostly at an exploratory stage, so discussions and inputs from the audience are more than welcome!

Venue: via Zoom

Event Official Language: English

Seminar

iTHEMS Math Seminar

Arithmetic dynamics on algebraic varieties

November 11 (Fri) at 14:00 - 16:30, 2022

Yosuke Matsuzawa (Associate Professor, Department of Mathematics, Graduate School of Science, Osaka Metropolitan University)

The study of self-maps of algebraic varieties is a relatively new and active area in mathematics. Such a self-map can be considered as a discrete dynamical system, and we can study the asymptotic properties of such systems from various points of views, including number theoretic viewpoint. I will introduce several problems in arithmetic dynamics and some of my results in this area.

Venue: Hybrid Format (Common Room 246-248 and Zoom)

Event Official Language: English

Conference

MCME SYMPOSIUM 2022 thumbnail

Co-hosted by iTHEMS

MCME SYMPOSIUM 2022

November 16 (Wed) - 17 (Thu), 2022

Takemasa Miyoshi (Team Leader, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS))
Hidetoshi Taya (Special Postdoctoral Researcher, iTHEMS)
Hidetoshi Nishimori (Specially Appointed Professor, Tokyo Institute of Technology)

"MCME SYMPOSIUM 2022" will be held at the Musashino Center of Mathematical Engineering (MCME), Musashino University. This symposium is free of charge and open to everyone.
Colleagues of iTHEMS will also be speaking. Below is an excerpt from the program.

Wednesday, November 16, 13:30 - 14:40 Takemasa Miyoshi
Thursday, November 17, 10:00 - 11:10 Hidetoshi Taya
Thursday, November 17, 14:50 - 16:00 Hidetoshi Nishimori

Registration is open until November 14. Please register from the related links below.

Organized by Musashino Center of Mathematical Engineering (MCME), Musashino University
Co-organized by RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS)

Venue: Hybrid Format (Room 301, Building 5, Ariake Campus, Musashino University and Zoom)

Seminar

iTHEMS Biology Seminar

Emergence of growth and dormancy from a kinetic model of the Escherichia coli central carbon metabolism

November 17 (Thu) at 18:00 - 19:00, 2022

Yusuke Himeoka (Assistant Professor, Universal Biology Institute, The University of Tokyo)

Physiological states of bacterial cells exhibit a wide spectrum of timescale. Under nutrient-rich conditions, most of the cells in an isogenic bacterial population grow at certain rates, while a small subpopulation sometimes stays in a dormant state where the growth rates slow down by orders of magnitude. For revealing the origins of such heterogeneity of timescales, we studied the kinetic model of Escherichia coli central carbon metabolism. We found that the model robustly exhibits both the growing- and the dormant state. Performing the model reduction, we have revealed the necessary conditions for the distinct behaviour, namely, the depletion of energy due to the futile cycle and its non-uniform impact on the kinetics because of the coexistence of the energy currency-coupled and uncoupled reactions as well as branching of the network.

Venue: via Zoom

Event Official Language: English

Seminar

iTHEMS Math Seminar

Tropical methods in Enumerative Geometry and Mirror Symmetry

November 25 (Fri) at 14:00 - 16:00, 2022

Michel Van Garrel (Assistant Professor, School of Mathematics, University of Birmingham, UK)

Abstract for the 1st hour: Enumerative Geometry has been a feature of mathematics from its beginnings, just think about the number of lines in the plane passing through 2 points. I will take you on a history of the subject and its relationship to other areas of mathematics and physics.

Abstract for the 2nd hour: Many problems in mathematics are solved by taking a limit and solving the limiting problem. Tropical geometry is a key technique that allows us to do this systematically. I will talk about the following problem. Take the complex projective plane S and an elliptic curve E in S. Count algebraic maps from the affine line into the complement S \ E. This counting problem is solved via tropical geometry as I will describe in this talk.

Venue: Hybrid Format (Common Room 246-248 and Zoom)

Event Official Language: English

Seminar

 thumbnail

iTHEMS Seminar

Efficient encoding of the Schrodinger equation on quantum computers

December 5 (Mon) at 14:00 - 15:30, 2022

Ermal Rrapaj (Postdoctoral Researcher, iTHEMS)

The continuous space Schrödinger equation is reformulated in terms of spin Hamiltonians. For the kinetic energy operator, the critical concept facilitating the reduction in model complexity is the idea of position encoding. A binary encoding of position produces a spin-1/2 Heisenberg-like model and yields exponential improvement in space complexity when compared to classical computing. Encoding with a binary reflected Gray code (BRGC), and a Hamming distance 2 Gray code (H2GC) reduces the model complexity down to the XZ and transverse Ising model respectively. Any real potential is mapped to a series of k-local Ising models through the fast Walsh transform. As a first step, the encoded Hamiltonian is simulated for quantum adiabatic evolution. As a second step, the time evolution is discretized, resulting in a quantum circuit with a gate cost that is better than the Quantum Fourier transform. Finally, a simple application on an ion-based quantum computer is provided as proof of concept.

References

  1. Improving Schrödinger Equation Implementations with Gray Code for Adiabatic Quantum Computers, Chia Cheng Chang, Kenneth S. McElvain, Ermal Rrapaj, and Yantao Wu, PRX Quantum 3, 020356, doi: 10.1103/PRXQuantum.3.020356
  2. Ermal Rrapaj, Kenneth S. McElvain, Chia Cheng Chang, Yantao Wu, André Walker-Loud, Gate Based Implementation of the Laplacian with BRGC Code for Universal Quantum Computers, doi: 10.48550/arXiv.2207.11647

Venue: Common Room #246-248, 2F Main Research Building, RIKEN / via Zoom

Event Official Language: English

Colloquium

iTHEMS Colloquium

The Epidemiology and Economics of Physical Distancing during Infectious Disease Outbreaks

December 14 (Wed) at 11:00 - 12:30, 2022

Troy Day (Professor, Head of Department, Department of Mathematics and Statistics, Queen's University, Canada)

People's incentives during an infectious disease outbreak influence their behaviour, and this behaviour can impact how the outbreak unfolds. Early on during an outbreak, people are at little personal risk of infection and hence may be unwilling to change their lifestyle to slow the spread of disease. As the number of cases grows, however, people may then voluntarily take extreme measures to limit their exposure. Political leaders also respond to the welfare and changing desires of their constituents, through public health policies that themselves shape the course of the epidemic and its ultimate health and economic repercussions. In this talk I will use ideas from the study of differential games to model how individuals’ and politicians’ incentives change during an outbreak, and the epidemiological and economic consequences that ensue when these incentives are acted upon. Motivated by the COVID-19 pandemic, I focus on physical distancing behaviour and the imposition of stay-at-home orders by politicians. I show that there is a fundamental difference in the political, economic, and health consequences of an infectious disease outbreak depending on the degree of asymptomatic transmission. If transmission occurs primarily by asymptomatic carriers, then politicians will be incentivized to impose stay-at-home orders earlier and for longer than individuals would like. Despite such orders being unpopular, however, they ultimately benefit all individuals. On the other hand, if the disease is transmitted primarily by symptomatic infections, then individuals are incentivized to stay at home earlier and for longer than politicians would like. In this case, politicians will be incentivized to impose back-to-work orders that, despite being unpopular, will again ultimately be to the benefit of all individuals.

This is joint work with David McAdams, Fuqua School of Business and Economics Department, Duke University.

Venue: via Zoom

Event Official Language: English

Seminar

iTHEMS Seminar

Lattice gauge theory in curved spacetimes

December 15 (Thu) at 14:00 - 15:30, 2022

Arata Yamamoto (Assistant Professor, Department of Physics, Graduate School of Science, The University of Tokyo)

Lattice gauge theory is a powerful computational approach in quantum field theory. It is also utilizable for investigating quantum phenomena in curved spacetimes, such as rotating frame, torsion, and gravitational backgrounds. In this talk, I would like to overview the formulation and results of lattice simulations in curved spacetimes.

References

  1. A. Yamamoto and Y. Hirono, Lattice QCD in Rotating Frames, Phys. Rev. Lett. 111, 081601 (2013), doi: 10.1103/PhysRevLett.111.081601
  2. A. Yamamoto, Lattice QCD in curved spacetimes, Phys. Rev. D 90, 054510 (2014), doi: 10.1103/PhysRevD.90.054510
  3. S. Benic and A. Yamamoto, Quantum Monte Carlo simulation with a black hole, Phys. Rev. D 93, 094505 (2016), doi: 10.1103/PhysRevD.93.094505
  4. S. Imaki and A. Yamamoto, Lattice field theory with torsion, Phys. Rev. D 100, 054509 (2019), doi: 10.1103/PhysRevD.100.054509

Venue: Common Room #246-248, 2F Main Research Building, RIKEN / via Zoom

Event Official Language: English

Person of the Week

Puttarak Jai-akson thumbnail

Self-introduction: Puttarak Jai-akson

2022-11-02

My name is Puttarak Jai-akson. I hail from Thailand and I obtained my bachelor’s degree there. I then moved to Canada to join the PSI program and completed my PhD at Perimeter Institute. I joined iTHEMS in November 2022 as a postdoctoral researcher and I have been very excited to learn, share, and cultivate new ideas with fellow researchers in this interdisciplinary environment. My research mainly focuses on theoretical aspects of gravity, leaning especially towards the theme of black holes, holography, and quantum gravity. I am interested in the idea of quasi-local holography, centering around the study of gravity in finite regions of spacetime where a wealth of fascinating mathematical structures and physics is unfolded. One topic which I have been currently pursued is the underlying correspondence between gravitational physics near finite null boundaries (such as black hole horizons) and Carrollian hydrodynamics, an unusual type of fluid dynamics living at the opposite corner to the conventional Navier-Stokes fluid dynamics. This correspondence will certainly shed light on the better understanding of black holes and their thermodynamical properties. I also believe that the connection between gravity and hydrodynamics will open a new route for the grand quest to quantize gravity.

Person of the Week

Maria Manuela Saez thumbnail

Self-introduction: Maria Manuela Saez

2022-11-02

Hola!, This is Maria Manuela Saez, an Argentinian astronomer and a new RIKEN - Berkeley postdoctoral fellow. I'm interested in astrophysics, and in particular, my research focuses on the study of core-collapse supernovae and the role that neutrinos play in these astrophysical environments. Core-collapse supernovae are the final evolutionary stage of massive stars and represent a long-awaited observation target for neutrino telescopes. To explain these events, one needs an interdisciplinary field of research that combines nuclear physics, particle physics, astrophysics and numerical simulations. Studying the signals that the supernovae' neutrino fluxes leave in the detectors, with an appropriate neutrino flavor discrimination, is possible to infer properties of the physics of the neutrinos involved and to study scenarios with non-standard neutrino properties. The structure of the neutrino mass spectrum and lepton mixing is imprinted into the detected signal. My goal is to contribute, from a theoretical perspective to the definition of strategies for detecting and studying neutrinos in large underground neutrino and dark matter detectors.
I'm looking forward to discussing and collaborating with iTHEMS people.

Person of the Week

Ermal Rrapaj thumbnail

Self-introduction: Ermal Rrapaj

2022-11-02

Hi, my name is Ermal Rrapaj, and I am a new RIKEN-Berkeley fellow. My research centers on the intersection of quantum many body physics and astrophysics. The general focus is on how particle interactions affect the properties of extreme environments such as supernovae and neutron stars and how they relate to earth experiments. The main research topics include properties of nuclei that could be tested in future experiments, neutrino nucleon matter interactions, transport properties of neutron stars, supernovae equation of state, and astrophysical implications from BSM particles. In recent years Ermal has been exploring how new technologies such as machine learning (neural networks) and quantum computing can aid in these research venues.

Person of the Week

Thomas Hitchcock thumbnail

Self-introduction: Thomas Hitchcock

2022-11-01

Hi, I’m Thomas Hitchcock. I grew up in the UK, studying Genetics and Systems Biology at the University of Cambridge, before moving up to the University of St Andrews to do my PhD in Evolutionary Genetics, and have now joined iTHEMS as an SPDR. I’m interested in why organisms appear the way they do, and how we can use evolutionary theory to better understand this. In practice, I’ve study two main flavours of problem, (1) when and why do organisms (and genes) come into conflict with one another, and (2) how are organisms (and genes) expected to weight different fitness trade-offs. To tackle these problems, I use a mix of population genetics and evolutionary game theory, and focus mainly on unusual genetic systems, life histories, and ecologies, which I hope might prove particularly clear tests of theory. I’m excited to discuss and learn from the wide variety of researchers at iTHEMS, and hopefully incorporate some new mathematical tools and frameworks into ecology and evolution.

Paper of the Week

Week 1, November 2022

2022-11-03

Title: Nuclei in Core-Collapse Supernovae Engine
Author: Shun Furusawa, Hiroki Nagakura
arXiv: http://arxiv.org/abs/2211.01050v1

If you would like to cancel your subscription or change your email address,
please let us know via our contact form.