iTHEMS Weekly News Letter

Press Release

Dr. Maria Giovanna Dainotti thumbnail
Dr. Shigehiro Nagataki thumbnail

The longest "rulers" in the universe -- Gamma-Ray Bursts associated with Kilonovae are the new standard candles


An international collaborative research group led by Maria Dinotti (Senior Research Scientist, iTHEMS) and Shigehiko Nagataki (Deputy Program Director, iTHEMS) has discovered that gamma-ray bursts (GRBs), which occur simultaneously with kilonovae, are effective as standard candles for measuring the distance of the universe.

The results of this research show the potential to make use of GRBs for cosmology in the near future, to estimate the amount of dark energy and dark matter in the universe.

Research News

Dark-matter candidate could display stringy effects in the lab thumbnail
Dr. Yoshimasa Hidaka thumbnail

Dark-matter candidate could display stringy effects in the lab


-Calculations show how theoretical ‘axionic strings’ could create odd behavior if produced in exotic materials in the lab-

A hypothetical particle that could solve one of the biggest puzzles in cosmology just got a little less mysterious. A RIKEN physicist and two colleagues have revealed the mathematical underpinnings that could explain how so-called axions might generate string-like entities that create a strange voltage in lab materials[1].

Seminar Report

Math-Phys joint Seminar by Dr. Naoto Shiraishi on November 10, 2020


On November 10, Dr. Naoto Shiraishi from Gakushuin University gave a talk entitled “Mathematics of thermalization in isolated quantum systems” at the iTHEMS Math-Phys joint seminar.

In the first part, he reviewed some results and problems of quantum thermalization. Besides, he explained the typicality of equilibrium states, the relaxation caused by large effective dimensions, and the weak/strong eigenstate thermalization hypothesis mathematically.

In the second part, the speaker discussed the difficulty of the thermalization problems and some of his results. Mainly, he showed the absence of local conserved quantities in the S=1/2 XYZ chain with a magnetic field.

The talk had many participants from in and out iTHEMS and many stimulating discussions.

Upcoming Events



The Unreasonable Effectiveness of Quantum Theory in Mathematics

November 26 at 10:00 - 11:30, 2020

Prof. Robbert Dijkgraaf (Director, Institute for Advanced Study in Princeton, USA)

November 26 at 10:00-11:30, 2020 (JST)
November 25 at 20:00-21:30, 2020 (EST)

The physical concepts of quantum theory, in particular of quantum gravity and string theory, have proven to be extremely powerful in addressing deep problems in pure mathematics, from knot invariants to algebraic geometry. Is there such a thing as “quantum mathematics”? Should we add Feynman diagrams, strings, branes and black holes to the language of mathematics?

Venue: via Zoom

Event Official Language: English


Academic-Industrial Innovation LectureCo-hosted by RIKEN SUURI CORPORATION

Toward the Practical Use of Quantum Computers

December 4 at 10:30 - 12:00, 2020

Dr. Shunji Matsuura (Visiting Scientist, iTHEMS / Fundamental Researcher, Quantum Simulation Division, 1QBit, Canada)


Venue: via Zoom

Event Official Language: Japanese

External Event

Sponsored by academistSupported by RIKEN SUURI CORPORATION

Presented by iTHEMS & academist - Do you really know what the black hole is?

December 6 at 14:00 - 16:00, 2020

Dr. Shigehiro Nagataki (Deputy Program Director, iTHEMS / Chief Scientist, Astrophysical Big Bang Laboratory, RIKEN Cluster for Pioneering Research (CPR))
Dr. Yoshiyuki Inoue (Senior Visiting Scientist, iTHEMS / Associate Professor, Department of Earth and Space Science, Graduate School of Science, Osaka University)
Dr. Yuki Yokokura (Senior Research Scientist, iTHEMS)

–From the latest theories and observations to the explanation of the Nobel Prize in Physics! An introduction to black holes from active physicists–

The 2020 Nobel Prize in Physics was awarded to Sir Roger Penrose, Prof. Dr. Reinhard Genzel and Prof. Andrea Ghez for their contributions to the theory and observation of black holes. Black holes have continued to provide hot topics in recent years, such as gravitational waves from black hole coalescence and black hole imaging, but do you really know what black holes are? Three cutting-edge black hole researchers will explain its identity and mystery.

Venue: via Online

Event Official Language: Japanese

Paper of the Week

Week 3 of November


Title: Classification of Magnetic Vortices by Angular Momentum Conservation
Author: Kenji Fukushima, Yoshimasa Hidaka, Ho-Ung Yee

Title: Variational Shape Approximation of Point Set Surfaces
Author: Martin Skrodzki, Eric Zimmermann, Konrad Polthier

Title: Firewall From Effective Field Theory
Author: Pei-Ming Ho, Yuki Yokokura

Title: Parity of the neutron consistent with neutron-antineutron oscillations
Author: Kazuo Fujikawa, Anca Tureanu

Title: Distance between collapsing matter and trapping horizon in evaporating black holes
Author: Pei-Ming Ho, Yoshinori Matsuo, Yuki Yokokura

Title: Test of Eigenstate Thermalization Hypothesis Based on Local Random Matrix Theory
Author: Shoki Sugimoto, Ryusuke Hamazaki, Masahito Ueda

Title: Liouvillian Skin Effect: Slowing Down of Relaxation Processes without Gap Closing
Author: Taiki Haga, Masaya Nakagawa, Ryusuke Hamazaki, Masahito Ueda

Title: Relativistic density functional theory with finite-light-speed correction for the Coulomb interaction: a non-relativistic-reduction based approach
Author: Tomoya Naito, Ryosuke Akashi, Haozhao Liang, Shinji Tsuneyuki

Title: Griffiths-McCoy singularity on the diluted Chimera graph: Monte Carlo simulations and experiments on the quantum hardware
Author: Kohji Nishimura, Hidetoshi Nishimori, Helmut G. Katzgraber

Title: Absence of fast scrambling in thermodynamically stable long-range interacting systems
Author: Tomotaka Kuwahara, Keiji Saito

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