In the Information Theory SG seminar on July 28th, Dr. Qibin Zhao gave us an exciting talk about the basics and applications of tensor networks (TNs) in machine learning. His talk was divided into three parts, (i) tensor methods for data representation, (ii) TNs in deep learning modeling, and (iii) frontiers and future trends. In the first part, he started with a graphical introduction of tensors and dimension reduction methods. He then presented the important question of how the imperfect data represented by tensors can be completed using the low-rank approximation, and introduced several possible approaches with impressive examples. Here he explained the TNs and decomposition methods in detail using diagrammatic notations, which can concisely express the tensor operations such as the contraction. In the second part, he talked about the useful application of TNs to model compression in machine learning. He illustrated the ways to represent the neural network model by tensors and to learn the weights through the contraction. Interestingly, the density matrix renormalization group (DMRG), which was originally proposed in the quantum physics field, may be used as a learning algorithm. In the last part, he showed an overview of recent topics on TNs and machine learning such as TNs for probabilistic modeling and supervised learning with projected entangled pair states (PEPS). Intriguingly, the topological structure of TNs can be optimized for a given image, and the learned topology significantly depends on the input data and is more complex than conventional simple structures such as lines, trees, or cycles. The clearly structured talk took us from the basics to the cutting-edge subjects, and there were many questions and discussions during the talk. We are deeply grateful to Dr. Qibin Zhao for his excellent talk on the fast-growing interdisciplinary field.

Reported by Kyosuke Adachi

On July 29th, Mayumi Seto (Nara Women's University) gave a talk on the application of thermodynamics to microbial modeling. She first introduced some important concepts of adenosine tri-phosphate (ATP), its synthesis in biology, and chmotrophic interactions between microorganisms. She then moved on to mathematical models explicitly incorporating energy flows in the microbial interactions. She finally gave implications from her work for future and ongoing studies, and after the talk we casually discussed her exciting projects.
For me, she was the person whom I met on the very first visitation at Kyushu University in 2009 when I was, as an undergrad student at another university, yet unsure to start my Ph.D. at Kyushu University or not, and I'm sure her kind and encouraging guidance was one of the decisive factors for me being here as a researcher. Thanks again for the fantastic talk, Mayumi!

Reported by Ryosuke Iritani

My name is Congcong Le from China, and I join iTHEMS on August 1st 2021 as a Postdoctoral Researcher. After graduation, I came to the Institute of Physics, Chinese Academy of Sciences to study theoretical physics, and obtained my PhD in July 2017. My research focuses on the theoretical study in condensed matter systems, including unconventional superconductivity, strongly correlated system, and novel topological system (topological insulators, Dirac semimetal, Weyl semimetal), and I start to be interested in twisted bilayers and topological phases in the non-Hermitian systems. I have enjoyed using mathematics to explore condensed matter physics and working with theorists and experimenters. In my spare time, I like Chinese chess, badminton, table tennis and climbing.

Title: LMC N132D: A mature supernova remnant with a power-law gamma-ray spectrum extending beyond 8 TeV
Author: H. E. S. S. Collaboration
arXiv: http://arxiv.org/abs/2108.02015v1

Title: Relativistic spin hydrodynamics with torsion and linear response theory for spin relaxation
Author: Masaru Hongo, Xu-Guang Huang, Matthias Kaminski, Mikhail Stephanov, Ho-Ung Yee
arXiv: http://arxiv.org/abs/2107.14231v1

Title: Convergence of a finite difference scheme for the Kuramoto--Sivashinsky equation defined on an expanding circle
Author: Shunsuke Kobayashi, Shigetoshi Yazaki
arXiv: http://arxiv.org/abs/2108.00593v1

Title: Locally equivalent quasifree states and index theory
Author: Chris Bourne
arXiv: http://arxiv.org/abs/2108.01230v1

Title: Toward ab initio determination of charge symmetry breaking strength of Skyrme functionals
Author: Tomoya Naito, Gianluca Colò, Haozhao Liang, Xavier Roca-Maza, Hiroyuki Sagawa
arXiv: http://arxiv.org/abs/2107.14436v1