News
161 news in 2023

20230802
Person of the WeekSelfintroduction: Steffen Backes
Hello! My name is Steffen Backes, and I just joined RIKEN Quantum as a Senior Scientific Researcher. My research interest is focused on the physics and phenomena that can be found in strongly correlated electron systems, such as transition metal oxides, cuprate and ironbased superconductors, nickelate materials, or other lowdimensional lattice systems. In these systems the Coulomb repulsion between electrons gives rise to unexpected emergent phenomena such as magnetism, charge order, superconductivity, the metaltoinsulator transition, changes in their optical properties, and many more. My particular interest lies in going beyond an effective singleparticle description of the electronic system, using perturbative and nonperturbative methods. For this, I am employing the GW approximation, Dynamical meanfield theory and its extensions such as cluster methods, or combinations in the form of GW+DMFT. In iTHEMS I will investigating how current Quantum processors, or "Noisy Intermediate Scale Quantum" (NISQ) devices can be used to solve the problems we encounter when studying such correlated electron systems with stateoftheart numerical methods. Since these devices are inherently noisy, the development of faulttolerant algorithms is one of my major goals.

20230802
Person of the WeekSelfintroduction: Yaokun Lei
My name is YaoKun Lei, and I joined iTHEMS in August 2023. I am originally from a city in the south of China. After finishing my undergraduate studies, I pursued a Ph.D. at Peking University, where I focused on studying the significant role of dynamic solvent effects in chemical reactions in condensed phases using enhanced sampling methods. Upon completing my Ph.D., I became a visiting scholar at the ShenZhen Bay Laboratory. During this period, I developed efficient strategies for rare event sampling and reaction coordinate analysis without prior knowledge of the reaction mechanism, using Reinforcement Learning and likelihood maximization techniques. In July 2021, I joined Theoretic Molecular Science Laboratory at RIKEN. Over the past two years, my research has been centered around developing accurate, efficient, and transferable machine learning force fields for systems embedded in external potentials, with the aim of accelerating QM/MM simulations using multiscale equivariant graph convolution networks. Looking ahead, I am enthusiastic about leveraging quantum computing to accelerate largescale molecular dynamics simulations. Specifically, I plan to utilize highprecision quantum computational results to expedite the parameterization of machine learning force fields. Additionally, I aim to enhance sampling in highdimensional spaces through quantum computing. During my time at iTHEMS, I hope to have the opportunity to collaborate with researchers from different disciplines and embark on exciting new explorations.

20230727
Paper of the WeekWeek 5, July 2023
Title: Universal properties of repulsive selfpropelled particles and attractive driven particles Author: Hiroyoshi Nakano, Kyosuke Adachi arXiv: http://arxiv.org/abs/2306.17517v1

20230726
Seminar ReportQuantum Matter Seminar by Xinloong Han on July 24, 2023
On July 24th, 2023, quantum matter SG hosted a seminar entitled "Electronic instabilities emerging from higherorder van Hove singularities", and the guest speaker was Xinloong Han, a Postdoctoral Fellow at the Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, China. Xinloong Han started by introducing van Hove singularity (VHS). Building on the conventional understanding of VHS points, Han introduced the concept of higherorder VHSs, which have recently been explored in ABCstacked trilayer graphene and twisted bilayer graphene. He elucidated the differences between conventional VHSs and higherorder VHSs, paving the way for a discussion on the enhanced nematicity driven by large flavor number with higherorder VHSs on the square and Kagome lattices. Towards the conclusion of his talk, Han shed light on the possibility of robust topological superconductivity emerging on the square lattice due to the interplay of spinorbital coupling and higherorder VHSs. This revelation presented a captivating insight into the advancements in the study of topological superconductors. Reported by ChingKai Chiu

20230721
Hot TopicThe Discovery Evening was held on June 22 at Wako Campus
The second onsite Discovery Evening since the COVID19 pandemic was held on June 22 at Wako Campus. 35 people attended the event, which was organized by the Research Personnel Affairs Section, RIKEN. José Said GutiérrezOrtega (Special Postdoctoral Researcher, iTHEMS) was one of the two speakers in the event. He gave a presentation titled "Natural history of cycads: Deciphering the Rosetta Stone of plant evolution." He explained that cycads existed from the time of the dinosaurs, but they were able to live on despite the dinosaurs going extinct. For more details, please visit the RIKENETIC website through the related link below. To access RIKENETIC, you will need to use the intranet.

20230720
Paper of the WeekWeek 4, July 2023
Title: Numerical simulation of photospheric emission in long gammaray bursts: prompt correlations, spectral shapes, and polarizations Author: Hirotaka Ito, Jin Matsumoto, Shigehiro Nagataki, Donald C. Warren, Maxim V. Barkov, Daisuke Yonetoku arXiv: http://arxiv.org/abs/2307.10023v1 Title: Continuum limit for Laplace and Elliptic operators on lattices Author: Keita Mikami, Shu Nakamura, Yukihide Tadano arXiv: http://arxiv.org/abs/2307.08894v1 Title: 4D Weyl Anomaly and Diversity of the Interior Structure of Quantum Black Hole Author: PeiMing Ho, Hikaru Kawai, Henry Liao, Yuki Yokokura arXiv: http://arxiv.org/abs/2307.08569v1 Title: Quasinormal modes of black holes encircled by a gravitating thin disk Author: CheYu Chen, Petr Kotlařík arXiv: http://arxiv.org/abs/2307.07360v1 Title: Complete characterization of robust perfect adaptation in biochemical reaction networks Author: Yuji Hirono, Ankit Gupta, Mustafa Khammash arXiv: http://arxiv.org/abs/2307.07444v1 Title: Cosmic ray processes in galactic ecosystems Author: Ellis R. Owen, Kinwah Wu, Yoshiyuki Inoue, H. Y. Karen Yang, Alison M. W. Mitchell arXiv: http://arxiv.org/abs/2306.09924v2 Title: SVD Entanglement Entropy Author: Arthur J. Parzygnat, Tadashi Takayanagi, Yusuke Taki, Zixia Wei arXiv: http://arxiv.org/abs/2307.06531v1

20230720
Seminar ReportDMWG Seminar by Slivia Manconi on July 10, 2023
As a nature of dark matter that feels gravity, dark matter in our Universe forms halos, which are gravitationallybounded macroscopic structures. The halo structure is highly hierarchical and the halo of our Milky Way, for example, hosts many subhalos inside. However, smaller halos below a certain scale could not be visible because they cannot host galaxies. If we look at the sky in gammaray wavelength, there are lots numbers of bright sources. Most of them are socalled active galactic nuclei (AGN), which are related to the powerful jet activities of black holes. A certain portion of point sources are not categorized yet. They could be AGNs, while it is also possible that they are bright due to DM annihilation occurring in compact and small subhalos in our Galaxy. Neural networks, which are tools we have obtained in this era, powerfully help us to obtain insights into the properties of unknown gammaray sources. Properties of known sources such as spectrum and population serve as data for the supervision of the neural network. The trained network is used to look for outliers in the gammaray unknown sources which can be candidates for subhalos emitting gammarays by DM annihilations. In this way, a conservative upper limit on the annihilation crosssection of DM is derived. The scheme is highly flexible and has many possibilities for extensions. In the near future, a huge amount of data, which is far beyond human ability to analyze all, from experiments in multiple wavelengths and probes should appear. The future of DM study assisted with machine learning should be bright. Reported by Nagisa Hiroshima

20230713
Paper of the WeekWeek 3, July 2023
Title: On the distance from a matrix to nilpotents Author: Michiya Mori arXiv: http://arxiv.org/abs/2307.04463v1 Title: Neural Polytopes Author: Koji Hashimoto, Tomoya Naito, Hisashi Naito arXiv: http://arxiv.org/abs/2307.00721v2

20230707
Seminar ReportABBLiTHEMS Joint Astro Seminar by Takatoshi Ko on July 7, 2023
Iras 00500+6713 is a bright nebula in the infrared, and Xray observations show it consists of diffuse region and strong illuminated central region. In addition, optical spectral observations have recently revealed that fast wind with about 15,000 km/s is blowing from the massive white dwarf at the center. The properties of this nebula and white dwarf are very similar to those theoretically predicted by the binary white dwarf merger. In addition, its position on the celestial sphere and the extent make it a prime candidate for the remnant of SN 1181, a historical supernova. In this seminar, Mr. Takatoshi Ko proposed that such a multilayered structure is formed by the collision between the remnant of SN 1181 and the stellar wind blowing from the central white dwarf, and succeeded in constructing a model that is consistent with the multiwavelength observations. The results show that the progenitor of SN 1181 is a binary white dwarf with 1.31.9 solar mass and that their merger triggered an explosion that ejected mass with 0.20.6 solar mass to form the present object. The extent of the Xray source concentrated in the center reveals that these winds began blowing within the last 30 years, and Mr. Takatoshi Ko discussed this property as well. Reported by Shigehiro Nagataki

20230706
Paper of the WeekWeek 2, July 2023
Title: Stringnet formulation of Hamiltonian lattice YangMills theories and quantum manybody scars in a nonabelian gauge theory Author: Tomoya Hayata, Yoshimasa Hidaka arXiv: http://arxiv.org/abs/2305.05950v1 Title: HBT signature for clustered substructures probing primordial inhomogeneity in hot and dense QCD matter Author: Kenji Fukushima, Yoshimasa Hidaka, Katsuya Inoue, Kenta Shigaki, Yorito Yamaguchi arXiv: http://arxiv.org/abs/2306.17619v1

20230703
Person of the WeekSelfintroduction: Jan SchuetteEngel
Hi, I'm Jan SchütteEngel and I recently started as a RIKENBerkeley fellow. My research focusses on gravitational waves (GWs) from the early and late universe. In particular, I'm interested in cosmological and astrophysical GW sources and what we can learn from the emitted GW signals about new physics phenomena. We expect many GW signals which encode new physics phenomena over a broad frequency range. Therefore, I also investigate novel detection ideas for GWs in frequency regimes that are difficult to probe with laser interferometers. Finally, I am working on novel ideas for axion dark matter direct detection. This line of research is highly interdisciplinary and often uses techniques from condensed matter physics and quantum sensing.

20230629
Paper of the WeekWeek 5, June 2023
Title: The Centimeter to Submillimeter Broad Band Radio Spectrum of the Central Compact Component in A Nearby TypeII Seyfert Galaxy NGC 1068 Author: Tomonari Michiyama, Yoshiyuki Inoue, Akihiro Doi arXiv: http://arxiv.org/abs/2306.15950v1 Title: Fractional time differential equations as a singular limit of the KobayashiWarrenCarter system Author: Yoshikazu Giga, Ayato Kubo, Hirotoshi Kuroda, Jun Okamoto, Koya Sakakibara, Masaaki Uesaka arXiv: http://arxiv.org/abs/2306.15235v1 Title: Spin transport between polarized Fermi gases near the ferromagnetic phase transition Author: Tingyu Zhang, Daigo Oue, Hiroyuki Tajima, Mamoru Matsuo, Haozhao Liang arXiv: http://arxiv.org/abs/2306.13536v1

20230622
Paper of the WeekWeek 4, June 2023
Title: Breaking new ground for quantum and classical simulations of $\mathrm{SU(3)}$ YangMills theory Author: Tomoya Hayata, Yoshimasa Hidaka arXiv: http://arxiv.org/abs/2306.12324v1 Title: Revisiting the extraction of charge radii of $^{40}$Ca and $^{208}$Pb with muonic atom spectroscopy Author: Hui Hui Xie, Tomoya Naito, Jian Li, Haozhao Liang arXiv: http://arxiv.org/abs/2306.09026v1 Title: The Average Number of Goldbach Representations and ZeroFree Regions of the Riemann ZetaFunction Author: Keith Billington, Maddie Cheng, Jordan Schettler, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2306.09102v1 Title: Resonant orbits of rotating black holes beyond circularity: discontinuity along parameter shift Author: CheYu Chen, HsuWen Chiang, Avani Patel arXiv: http://arxiv.org/abs/2306.08356v1 Title: Exotic Dehn twists on 4manifolds Author: Hokuto Konno, Abhishek Mallick, Masaki Taniguchi arXiv: http://arxiv.org/abs/2306.08607v1 Title: Evidence for the utility of quantum computing before fault tolerance Author: Youngseok Kim, Andrew Eddins, Sajant Anand, Ken Xuan Wei, Ewout van den Berg, Sami Rosenblatt, Hasan Nayfeh, Yantao Wu, Michael Zaletel, Kristan Temme, Abhinav Kandala Journal Reference: Nature 618, 500–505 (2023) doi: https://doi.org/10.1038/s41586023060963

20230622
Press ReleaseControl Simulation Experiments of Extreme Events  New Theories for Extreme Weather Control
A collaborative research team led by Takemasa Miyoshi (Team Leader, Data Assimilation Research Team, RIKEN Center for Computational Science (RCCS) / Deputy Program Director, iTHEMS) has revealed the controllability to prevent the occurrence of extreme phenomena such as heavy rainfall and high temperatures through lowdimensional ideal experiments. This research achievement is expected to contribute to the development of theoretical research aimed at controlling intensifying typhoons and torrential rains, thereby mitigating the threat of extreme weather disasters. For more details, please visit the related link.

20230621
Hot TopiciTHEMS Science Outreach Workshop 2023 was held on June 1618, 2023
On June 1618, we had Meeting on Outreach of RIKEN iTHEMS 2023 @Sendai & Zoom. This year the meeting was held at TOKYO ELECTRON House of Creativity 3F, Lecture Theater, Katahira Campus, Tohoku University. It was organized by RIKEN iTHEMS and Mathematical Science Center for Cocreative Society of Tohoku University and coorganised by Tohoku Forum for Creativity, Organization for Research Promotion, Tohoku University and RIKEN CPR, Prediction Science Laboratory. There were 37 people participated at TOKYO ELECTRON House of Creativity and 13 more by zoom. There were 19 talks at the venue and 2 talks by zoom. 4 talks were by members of iTHEMS explaining recent development in various fields in sciences. 8 talks were from universities or institutes on different aspects of research, where 2 were by exmembers of iTHEMS. 8 talks were given by journalists and 1 by MEXT. There was also 1 poster by a journalist, a display of photos of fingers of mathematicians, a display of monthly academic magazine. The participants consist of 9+4 members from RIKEN, 14+2 from universities and institutes, and 14+7 journalists (at venue + by zoom). The venue was so nicely organized and ideal for the meeting of 30  40 participants, and the lounge next to the conference room was comfortably clouded which greatly contributed the success of the meeting. We organized social gathering on the two evenings and which were also successful. We thank very much for the help of Profs. Yoshiaki Maeda and Hiroshi Suito for the warm hospitality. By the success of this meeting, we hope the continuation of Journalist in residence program and this workshop next year. Reported by Takashi Tsuboi

20230620
Press ReleaseEvidence for the utility of quantum computing before fault tolerance
Quantum computing promises to offer substantial speedups over its classical counterpart for certain problems. However, the implementation of faulttolerant quantum circuits is out of reach for current processors. The recent paper by Yantao Wu (RIKEN iTHEMS) together with the IBM and UC Berkeley teams demonstrates the measurement of accurate expectation values on a noisy IBMQ 127qubit processor for circuit volumes at a scale beyond bruteforce classical computation. In the regime of strong entanglement for the temporal dynamics of the transversefield Ising model, the quantum computer provides correct results for which leading classical approximations such as the tensor network methods break down. This represents evidence for the utility of quantum computing in a prefaulttolerant era. At the same time, their results will motivate and help advance classical approximation methods as both approaches serve as valuable benchmarks of one another.

20230619
Seminar ReportiTHEMS Biology Seminar by Dr. Yu Okamura on May 25, 2023
We had the pleasure to have Dr. Yu Okamura (The University of Tokyo) as an invited speaker of our Biology seminar of May 25th, 2023. Dr. Okamura introduced us to the mechanism that allow herbivory of Pieris butterflies on Brassicaceae plants (plants of the group of the mustard). Brassicaceae, as well as most plants, will defend from herbivores by producing chemical compounds that can be lethal, but at the same time, insects will need to evolve strategies to elude the chemical defenses of the plants. This relationship leads to an interesting coevolutionary pathway that has not been widely explored from the genomic perspective. In his study system, Dr. Okamura has performed experiments to research how the toxic chemical compounds derived from glucosinolates of plants are eluted by their butterfly herbivores thanks to the expression of two specific genes that produce proteins that decompose the glocusinolates into nonlethal metabolites. One of the two genes (NSP gene) is known to be expressed in most Pieris butterflies that feed on Brassicaceae plants, but in his research, Dr. Okamura found that another gene (MA gene) is complementary of the effect of the NSP gene. Using genome editing techniques (CRISPR/Cas9), Dr. Okamura showed that the absence of NSP or MA genes can be lethal for herbivores. It is concluded that, in combination, NSP and MA genes are necessary for Pieris butterflies to maintain herbivory on a wide variety of plants in the Brassicacae family. Reported by José Said GutiérrezOrtega

20230615
Paper of the WeekWeek 3, June 2023
Title: Shear and interface modes in neutron stars with pasta structures Author: Hajime Sotani arXiv: http://arxiv.org/abs/2306.07531v1 Title: Light Scalar Meson and Decay Constant in SU(3) Gauge Theory with Eight Dynamical Flavors Author: Lattice Strong Dynamics Collaboration, R. C. Brower, E. Owen, C. Rebbi, C. Culver, D. Schaich, K. K. Cushman, G. T. Fleming, A. Gasbarro, A. Hasenfratz, E. T. Neil, J. Ingoldby, X. Y. Jin, J. C. Osborn, E. Rinaldi, P. Vranas, E. Weinberg, O. Witzel arXiv: http://arxiv.org/abs/2306.06095v1 Title: Effective model and pairing tendency in bilayer Nibased superconductor La$_3$Ni$_2$O$_7$ Author: Yuhao Gu, Congcong Le, Zhesen Yang, Xianxin Wu, Jiangping Hu arXiv: http://arxiv.org/abs/2306.07275v1 Title: An unconditional Montgomery Theorem for Pair Correlation of Zeros of the Riemann Zeta Function Author: Siegfred Alan C. Baluyot, Daniel Alan Goldston, Ade Irma Suriajaya, Caroline L. TurnageButterbaugh arXiv: http://arxiv.org/abs/2306.04799v1 Title: On a smoothed average of the number of Goldbach representations Author: Daniel A. Goldston, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2306.04807v1

20230614
Press ReleaseRicoh and RIKEN Develop Unique Algorithm to Visualize Changing Points of Technological Trends from Literature Data
Ricoh Co., Ltd. (President and CEO: Akira Oyama) and RIKEN iTHEMS (Aoyama Hideaki, Senior Visiting Scientist / Wataru Soma, Visiting Scientist) have jointly developed an algorithm to quantitatively measure and understand the points of change in new trends from existing technical literature data. For more details, please visit Ricoh group's website through the related link below.

20230613
Seminar ReportiTHEMS Math Seminar by Mr. Kan Kitamura on June 7, 2023
In iTHEMS Math Seminar on June 7, 2023, Kan Kitamura gave us a talk on his recent research on quantum groups. In the first half of the talk, he introduced the definition of C*algebras and compact quantum groups. In the latter half of the talk, he explained his theorem on the classification of the discrete quantum subgroups of the quantum double of qdeformed simple Lie groups. The talk was highly clear and stimulating. Reported by Mizuki Oikawa

20230612
Research NewsRIKEN NEWS: Unraveling the Puzzle of Complex Ecosystems with Mathematical Models
Ryosuke Iritani (Senior Research Scientist, iTHEMS) is interviewed on the RIKEN website. Nature is home to a multitude of ecosystems, each teeming with a rich variety of organisms. Within these intricate webs of life, diverse species interact and adapt, giving rise to complex and fascinating structures. However, comprehending the inner workings of these ecosystems poses a significant challenge, owing to their inherent complexity. At RIKEN, a team of dedicated researchers is harnessing the power of mathematical models to elucidate the intricacies of ecosystems and unlock their enigmatic nature. To shed light on this endeavor, we turn to Ryosuke Iritani, who graciously provides us with insights into their ongoing work. To read more, please visit the related link.

20230608
Paper of the WeekWeek 2, June 2023
Title: Nuclear mass predictions based on deep neural network and finiterange droplet model (2012) Author: To Chung Yiu, Haozhao Liang, Jenny Lee arXiv: http://arxiv.org/abs/2306.04171v1 Title: Finiterange effect in the twodimensional densityinduced BCSBEC crossover Author: Hikaru Sakakibara, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2306.02127v1 Title: Quasimaps to quivers with potentials Author: Yalong Cao, Gufang Zhao arXiv: http://arxiv.org/abs/2306.01302v1 Title: Topological quadraticnode semimetal in a photonic microring lattice Author: Zihe Gao, Haoqi Zhao, Tianwei Wu, Xilin Feng, Zhifeng Zhang, Xingdu Qiao, ChingKai Chiu, Liang Feng Journal Reference: Nature Communications 14, 3206 (2023) doi: https://doi.org/10.1038/s41467023388613 Title: The origin of MeV gammaray diffuse emission from the inner Galactic region Author: Naomi Tsuji, Yoshiyuki Inoue, Hiroki Yoneda, Reshmi Mukherjee, Hirokazu Odaka doi: https://doi.org/10.22323/1.417.0037 arXiv: http://arxiv.org/abs/2306.00290v1

20230606
Person of the WeekSelfintroduction: Derek Beattie Inman
Hello! My name is Derek Inman, and I am a scientist at iTHEMS whose research is focused on cosmology. Our Universe contains a substantial amount of dark matter the behavior of which we broadly know, but the composition of which we don’t. I try to understand how different ideas for what dark matter is (particles? black holes? something else?) change how the Universe looks and evolves at various times and length scales. I am particularly interested in cosmological structure formation, which rapidly becomes a nonlinear problem and so I tend to use numerical simulations run on supercomputers to understand the relevant physics.

20230601
Paper of the WeekWeek 1, June 2023
Title: Survival Probability of Unstable States in CoupledChannels  nonexponential decay of "thresholdcusp" Author: Wren A. Yamada, Osamu Morimatsu, Toru Sato, Koichi Yazaki arXiv: http://arxiv.org/abs/2305.11695v2 Title: Chiral fermion in the Hamiltonian lattice gauge theory Author: Tomoya Hayata, Katsumasa Nakayama, Arata Yamamoto arXiv: http://arxiv.org/abs/2305.18934v1 Title: QCDBased Charge Symmetry Breaking Interaction and OkamotoNolenSchiffer Anomaly Author: Hiroyuki Sagawa, Tomoya Naito, Xavier RocaMaza, Tetsuo Hatsuda arXiv: http://arxiv.org/abs/2305.17481v1

20230601
Seminar ReportQuantum uncertainty of fields and its effect on entanglement generation in quantum particles by Mr. Yuki Sugiyama on May 31, 2023
The unification of gravity and quantum mechanics is one of the important problems. To elucidate the theory of quantum gravity, it is becoming more and more important to get any hint of the quantum nature of gravity. In particular, the quantumgravityinducedentanglement of masses (QGEM) scenario, which is expected to observe the quantum nature of nonrelativistic gravity, has recently attracted great attention. In this talk, Sugiyamasan showed the effect of relativistic fields on entanglement generation based on quantum field theory. We also discussed the relationship between the entanglement generation and quantum uncertainty of the fields. Reported by Shigehiro Nagataki

20230531
Seminar ReportiTHEMS Theoretical Physics Seminar by Dr. Masaki Tezuka on May 30, 2023
On May 30, Dr. Masaki Tezuka gave a talk on Spectral correlations and scrambling dynamics in SachdevYeKitaev(SYK) type models. He explained his recent studies on quantum chaotic features, quantum scrambling, and connections to holography and quantum error corrections in the SYKtype models. Reported by Yuta Sekino

20230530
AwardDr. Tomoki Ozawa selected to receive an Asian Young Scientist Fellowship
Dr. Tomoki Ozawa (Visiting Scientist, iTHEMS / Associate Professor, Advanced Institute for Materials Research (AIMR), Tohoku University) has been selected to receive an Asian Young Scientist Fellowship 2023. This fellowship aims to encourage and support young Asian scientists in three fields: 1) Life Science, 2) Physical Science, and 3) Mathematics and Computer Science. Dr. Ozawa has been selected in his contribution to the topological states in photonics crystals with synthetic dimensions and his exploration in the direction of manybody physics in synthetic and tunable AMO platforms. For more information, please see the related links.

20230528
Seminar ReportExploring GPT’s Influence on Natural Science and Mathematics on May 17, 2023
The emergence of ChatGPT has shocked the world. Its influence on our society is inestimable, both for its possibility and its potential risk. Together with MLPhys (Foundation of “Machine Learning Physics”), we held a workshop “Exploring GPT’s Influence on Natural Science and Mathematics” on 17th May, to discuss the influence of GPT particularly on natural science and mathematics. An introductory lecture on GPT (generative pretrained transformer) and LLM (large language model) was given by Mr. Shota Imai (The University of Tokyo), and an introductory lecture on proof assistant system (automated theorem proving) was given by Dr. Yoshihiro Mizoguchi (Kyushu University). Around 30 people attended in place, and over 400 people attended the workshop online. Lively discussion took place among specialists of Mathematics, Physics and Computer science. Reported by Taketo Sano (iTHEMS, RIKEN)

20230526
Seminar ReportMathPhys Seminar by Dr. Masazumi Honda on February 16, 2023
On Febururary 16, Masazumi Honda gave a talk. He explained his recent results on the relationship between Riemann hypothesis and fourdimensional N=4 supersymmetric YangMills theory. Reported by Keita Mikami

20230525
Paper of the WeekWeek 4, May 2023
Title: A Stochastic Approach To Reconstruct Gamma Ray Burst Lightcurves Author: Maria G. Dainotti, Ritwik Sharma, Aditya Narendra, Delina Levine, Enrico Rinaldi, Agnieszka Pollo, Gopal Bhatta arXiv: http://arxiv.org/abs/2305.12126v2 Title: Chiral anomaly in a (1+1)dimensional Floquet system under highfrequency electric fields Author: Kenji Fukushima, Yoshimasa Hidaka, Takuya Shimazaki, Hidetoshi Taya arXiv: http://arxiv.org/abs/2305.11432v1

20230525
Seminar ReportiTHEMS Math Seminar by Dr. Kohei Hayashi on May 24, 2023
On May 24, there was a math seminar by Kohei Hayashi. In the first part of his talk, he start by explaining the idea of the hydrodynamic limit and the fluctuating hydro dynamic limit. He then explained Markov chain and how to obtain the diffusion equation. In the second part, he explained KPZ equation and its universality. Reported by Keita Mikami

20230522
Hot TopicRyosuke Iritani gave a scientific outreach talk at Mathcafe on May 14, 2023
On Sunday 14th May, Ryosuke Iritani gave a scientific outreach talk at Mathcafe. He focused on spatial biodiversity as a chief topic and how to use mathematics to estimate, and make inferences for, the biodiversity. He explained the measurement of biodiversity from the axiomatic viewpoint, that is, he explained what properties should be satisfied by the quantity that is supposed to measure biodiversity. He then moved on to explaining an application of generating functions to biodiversity measures. He finished his talk by saying that mathematics is not only useful to science but also a lifetime fun hobby.

20230522
Seminar ReportABBLiTHEMS Joint Astro Seminar by Mr. Vincenzo Sapienza on May 19, 2023
Synchrotron Xray emission in young supernova remnants (SNRs) is a powerful diagnostic tool to study the population of high energy electrons accelerated at the shock front. Mr. Sapienza and his collaborators performed a spatially resolved spectral analysis of the young Kepler's SNR, where they identify two different regimes of particle acceleration. In the north, where the shock interacts with a dense circumstellar medium (CSM), they found a more efficient acceleration than in the south, where the shock velocity is higher and there are no signs of shock interaction with dense CSM. They also studied the temporal evolution of the synchrotron flux, from 2006 to 2014. A number of regions show a steady synchrotron flux and equal cooling and acceleration times. However, they found some regions where they measured a significant decrease in flux from 2006 to 2014. Our results display a coherent picture of the different regimes of electron acceleration observed in Kepler's SNR. Also Mr. Sapienza presented some preliminary results on the SN 1987A project. Reported by Shigehiro Nagataki

20230518
Paper of the WeekWeek 3, May 2023
Title: Embedding and correlation tensor for XRP transaction networks Author: Abhijit Chakraborty, Tetsuo Hatsuda, Yuichi Ikeda arXiv: http://arxiv.org/abs/2305.09917v1 Title: Exploring $^3P_0$ Superfluid in Dilute SpinPolarized Neutron Matter Author: Hiroyuki Tajima, Hiroshi Funaki, Yuta Sekino, Nobutoshi Yasutake, Mamoru Matsuo arXiv: http://arxiv.org/abs/2305.08690v1 Title: Tensor category equivariant KKtheory Author: Yuki Arano, Kan Kitamura, Yosuke Kubota arXiv: http://arxiv.org/abs/2305.07255v1 Title: Firstorder phase transitions in YangMills theories and the density of state method Author: Biagio Lucini, David Mason, Maurizio Piai, Enrico Rinaldi, Davide Vadacchino arXiv: http://arxiv.org/abs/2305.07463v1

20230517
Hot TopicThomas Hitchcock gave a short talk at Nerd Nite Tokyo on April 21, 2023
On Friday 21st April, Thomas Hitchcock gave a short talk at Nerd Nite Tokyo entitled “Sex Education: reproductive diversity across the tree of life”. There he talked to a general audience about the range of ways that organisms may reproduce, from those organisms that simply make copies of their own genes (asexual reproduction), to those that mix them with others (sexual reproduction), and those that can do both (facultative sex). He discussed the different mechanisms that organisms may use to decide whether to reproduce as a female (producing eggs) or male (producing sperm), and how genes may pass differently to offspring through these two routes, illustrating these ideas with stories about spoonworms, fungus gnats, and rotifers. Finally, he stressed how evolution may work differently in these different reproductive systems, and so the importance of understanding this diversity for guiding our efforts in conservation, agriculture, and medicine.

20230515
Seminar ReportSpring Workshop on Quantum Gravity on April 26, 2023
Spring Workshop on Quantum Gravity, the first one in the lecture series Quantum Gravity Gatherings and cosponsored by NCTS, was a great success with about 50 participants, including some from Taiwan. First, Prof. Kawai's intensive lecture on quantum gravity was wonderful. In the basic part of the first half, he explained the physical aspects of the ordinary formulas found in textbooks on general relativity, from a quantum theoretical standpoint, and transformed the equations consistently, to arrive at physically clear results about quantum gravitational fields. In the latter part, he described the features of fieldtheoretic quantum gravity and its limitations. Through these, he showed us the importance of researching quantum gravity step by step from a fundamental point of view. All participants were interested in quantum gravity, and there was an atmosphere of togetherness in the room. During the lecture, a variety of questions, from the simple to the fundamental, were raised. During breaks, small discussions spontaneously occurred here and there in the common space. And in the short talk sessions, we were able to share each other's research and interests. The banquet on the first day of the event was a great opportunity to deepen friendship. Thus, this event provided many opportunities for learning, research, and exchange for the younger generation. Reported by Yuki Yokokura

20230512
Seminar ReportDMWG Seminar: DMline search in the Galactic Center with MAGIC telescope
Among kinds of dark matter (DM) candidates, weakly interacting massive particles (WIMPs) are the most intensively studied ones along their theoretical background and expectations for the signals in onEarth experiments. However, up to now, our understanding of the regime of m>O(1) TeV is still limited since we cannot produce them at colliders and cannot expect a sufficient interaction rate at underground recoil detectors. Highenergy astrophysical observations are powerful in probing that regime and projects all over the world are now searching for corresponding signals. When we look for signatures of DM from astrophysical data, it is necessary to consider contributions from astrophysics very carefully. The key signatures could be the morphology of the emission, the spectrum, and correlating signals in other kinds of observations, variabilities, and so on. If DM particles annihilate to produce photon pairs, the spectrum should show a monochromatic peak corresponding to the mass of DM, hence it is distinctive against the astrophysical emissions. MAGIC telescope, which locates in the Northern Hemisphere, only considers target objects in the northern sky previously. However, it actually can see the Galactic Center in a large inclination. For this case, the threshold of the analysis is worsened but the effective area is improved, then it can achieve a good sensitivity to highenergy emissions. Using 223h of observation at the Galactic Center with MAGIC, the line emission search is carefully performed. The determination of the "off" takes an important role in not overestimating the sensitivity and the sliding window technique is adopted regarding this point. The uncertainty of the DM density of the region of interest is also carefully discussed by performing the analysis applying both the cuspy and cored profiles. No signatures of the monochromatic gammaray from DM annihilation are found in this analysis hence we obtain upper limits of the annihilation crosssection. The sensitivity is comparable to the flux level of a wellmotivated Wino DM model which should exhibit annihilation lines around E~3TeV. This means that we are now approaching the era that to probe detailed particle models of DM with astrophysical observations. In the near future, observations with the Cherenkov Telescope Array will start operations and we can look into the detail of the models in combination with particle physics communities! Reported by Nagisa Hiroshima

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Paper of the WeekWeek 2, May 2023
Title: Ceratozamia rosea (Zamiaceae): A new species from the Northern Mountains of Chiapas, Mexico Author: José GarcíaGonzález, Miguel Angel PérezFarrera, José Said GutiérrezOrtega, Andrew P. Vovides, Pedro DíazJiménez Journal Reference: Phytotaxa 595(1): 7388 (2023) doi: https://doi.org/10.11646/phytotaxa.595.1.5 Title: Zamia magnifica (Zamiaceae, Cycadales): A New Rupicolous Cycad Species from Sierra Norte, Oaxaca, Mexico Author: Miguel Angel PérezFarrera, José Said GutiérrezOrtega, Mauricio Gerónimo MartínezMartínez, Michael Calonje Journal Reference: Taxonomy 3(2): 232249 (2023) doi: https://doi.org/10.3390/taxonomy3020017 Title: Nonexpansive and noncontractive mappings on the set of quantum pure states Author: Michiya Mori, Peter Šemrl arXiv: http://arxiv.org/abs/2305.05123v1 Title: HigherForm Symmetry and Eigenstate Thermalization Hypothesis Author: Osamu Fukushima, Ryusuke Hamazaki arXiv: http://arxiv.org/abs/2305.04984v1 Title: Quantum Velocity Limits for Multiple Observables: Conservation Laws, Correlations, and Macroscopic Systems Author: Ryusuke Hamazaki arXiv: http://arxiv.org/abs/2305.03190v1 Title: Hidden Conformal Symmetry from the Lattice Author: LSD Collaboration, T. Appelquist, R. C. Brower, K. K. Cushman, G. T. Fleming, A. Gasbarro, A. Hasenfratz, J. Ingoldby, X. Y. Jin, E. T. Neil, J. C. Osborn, C. Rebbi, E. Rinaldi, D. Schaich, P. Vranas, E. Weinberg, O. Witzel arXiv: http://arxiv.org/abs/2305.03665v1 Title: The impact of effective matter mixing based on threedimensional hydrodynamical models on the molecule formation in the ejecta of SN 1987A Author: Masaomi Ono, Takaya Nozawa, Shigehiro Nagataki, Alexandra Kozyreva, Salvatore Orlando, Marco Miceli, KeJung Chen arXiv: http://arxiv.org/abs/2305.02550v1

20230511
Person of the WeekSelfintroduction: Kohei Hayashi
Hi, my name is Kohei Hayashi. I am a visiting researcher as the postdoctral fellowship of Japan Society for the Promotion of Science (JSPS). So far, I have been working on explaining macroscopic behavior of some physical quantities from microscopic models. Especially, my interest lies in universality that arises in fluctuations of Markov processes. An important example of such universality class is the KardarParisiZhang universality class and it has been observed in various probabilistic models. I am trying to understand mechanisms or backgrounds of such universality in mathematically rigorous ways.

20230508
Hot TopicProbing Extreme Gravity with Ringing Black Holes
Naritaka Oshita (Visiting Scientist, iTHEMS) contributed to the chapter “Researches” in the membership journal of the physical society of Japan on the universality in a black hole ringing and its application to probe the nearhorizon physics of black holes. Also, a picture relevant to Naritaka Oshita’s research on a black hole ringing was selected as the cover art of the journal. You can visit the following web site of the Physical Society of Japan to access the contributions.

20230508
BookHandbook of Protistology
Editor: Euki Yazaki, et al. Language: Japanese Release date: May 10, 2023 This handbook covers a wide range of knowledge and the latest information on evolution, ecology, and the relationship between humans and various studies and new findings that have emerged from research on protists. The recent classification system is also organized. The contents include: What are protists? (cell structure, phylogeny and classification, macroevolution, symbiosis, ecology, model organisms) / Evolution and classification (Amoebozoa, Archaeplastida, Stramenopiles, Alveolata, and others) / Protist structure and ecology (life cycle, structure and function, symbiosis, genomics, environment and ecology, and interactions with humans) / Research methods.

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Paper of the WeekWeek 1, May 2023
Title: Nonlinear chiral kinetic theory Author: Kazuya Mameda arXiv: http://arxiv.org/abs/2305.02134v1 Title: Spatial deformation of manybody quantum chaotic systems and quantum information scrambling Author: Kanato Goto, Taozhi Guo, Tomoki Nosaka, Masahiro Nozaki, Shinsei Ryu, Kotaro Tamaoka arXiv: http://arxiv.org/abs/2305.01019v1

20230502
Hot TopicRIKEN iTHEMS signed a new MoU with Lawrence Berkeley National Laboratory (LBNL)
Reiner Kruecken (Director of the Nuclear Science Division of LBNL) and Tetsuo Hatsuda (Director of RIKEN iTHEMS) are the principal coordinators for LBNL and RIKEN iTHEMS, respectively, for this MoU [1]. The photo was taken in front of the desk of Ernest Lawrence [2], which is preserved at LBNL.

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Person of the WeekSelfintroduction: Rongyang Sun
My name is Rongyang Sun. I joined RIKEN in October 2021 as a Postdoctoral Researcher in RCCS and RQC. Now, I am very glad to hold this concurrent position in iTHEMS. As a fullstack researcher in computational quantum manybody physics, my ultimate goal is to understand the fantabulous nature of quantum manybody systems by taking advantage of modern supercomputing systems and quantum computers. Towards this goal, I am developing advanced tensor network algorithms, maintaining highperformance tensor computing software, and applying these tools to the study of strongly correlated systems like interacting electrons and frustrated spins. Meanwhile, I am also exploring the possibility of utilizing nearterm quantum computers to arrive at the same destination.

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Person of the WeekSelfintroduction: Tomonori Shirakawa
My name is Tomonori Shirakawa. I joined iTHEMS as a Senior Research Scientist in April 2023. I am interested in quantum manybody phenomena in condensed matter physics. To better understand quantum manybody phenomena, I have been working with various numerical methods. In particular, I have recently been exploring more efficient ways to solve quantum manybody problems using quantumclassical hybrid algorithms, quantum algorithms, and tensor network methods.

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Seminar ReportiTHEMS Biology Seminar by Mr. Naoki Konno on April 20, 2023
In April 20, Mr Naoki Konno (University of Tokyo) gave a fantastic talk about the machine leaning method for the prediction of evolution. The talk was entitled, “Machine learning predicts biological system evolution by gene gains and losses”. To my knowledge, this study using genome data of ~3000 species is one of few seminal attempts to theoretically predict longterm and systemlevel evolution. The seminar by Konno san was very clear and we understood the predictability of the proposed framework, called “Evodictor”. In the beginning of the talk, he kindly explained the theoretical basis about phylogenetic tree estimation and machine learning for nonspecialists for which we could enjoy and learn from his seminar a lot. Thank you, Konnosan for the great talk!! Reported by Gen Kurosawa

20230424
Research NewsRIKEN Research: Quantum ‘magic’ could help explain the origin of spacetime
A quantum property dubbed ‘magic’ could be the key to explaining how space and time emerged, a new mathematical analysis by three RIKEN physicists suggests [1]. It’s hard to conceive of anything more basic than the fabric of spacetime that underpins the Universe, but theoretical physicists have been questioning this assumption. “Physicists have long been fascinated about the possibility that space and time are not fundamental, but rather are derived from something deeper,” says Kanato Goto of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS). To read more, please visit the related link.

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Seminar ReportABBLiTHEMS Joint Astro Seminar by Dr. Kumiko Kotera on April 18, 2023
We are living exciting times: we are now able to probe the most violent events of the Universe with diverse messengers (cosmic rays, neutrinos, photons and gravitational waves). One challenge to complete the multimessenger picture resides in the highest energies, as no ultrahigh energy neutrinos have been observed yet. This challenge could be undertaken by the GRAND (Giant Radio Array for Neutrino Detection) project, which aims at detecting ultrahigh energy particles, with a colossal array of 200'000 antennas over 200'000 km2, split into ~20 subarrays of ~10'000 km2 deployed worldwide. In this talk, Kumiko Kotera presented preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution. Reported by Shigehiro Nagataki

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Paper of the WeekWeek 4, April 2023
Title: Investigating Time Evolution of Thermal Emission from the Putative Neutron Star in SN 1987A for 50+ Years Author: Akira Dohi, Emanuele Greco, Shigehiro Nagataki, Masaomi Ono, Marco Miceli, Salvatore Orlando, Barbara Olmi arXiv: http://arxiv.org/abs/2304.08418v1 Title: The Impacts of NeutronStar Structure and Base Heating on Type I XRay Bursts and Code Comparison Author: Guoqing Zhen, Guoliang Lv, Helei Liu, Akira Dohi, Bobuya Nishimura, Chunhua Zhu, Liyu Song, Weiyang Wang, Renxin Xu arXiv: http://arxiv.org/abs/2304.07197v1 Title: Plausible presence of new state in neutron stars with masses above $0.98M_{\rm TOV}$ Author: MingZhe Han, YongJia Huang, ShaoPeng Tang, YiZhong Fan doi: https://doi.org/10.1016/j.scib.2023.04.007 arXiv: http://arxiv.org/abs/2207.13613v2

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Research NewsRIKEN Research: Gravitational waves could indicate transition to strange quark matter
Telltale signatures in gravitationalwave signals from merging neutron stars should reveal what happens to matter at the extreme pressures generated during such mergers, calculations by RIKEN researchers predict [1]. If you took some water and compressed it with a piston, it would shrink as the molecules get pushed closer together. If you continued ramping up the pressure, you’d reach a point where the atoms collapse and form an ultradense soup of neutrons and protons. The only place in the Universe where this happens is neutron stars, the collapsed remnants of burnedout stars, and it produces mindboggling densities—one teaspoon of such material weighs several hundred billion kilograms. But what would happen if you continued to increase the pressure still further? Not even astrophysicists know the answer to that. To read more, please visit the related link.
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