News
118 news in 2019
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2019-07-18
Hot Topic
Summary of the 1-day Workshop on Quantum Gravity
What is spacetime? In order to discuss this fundamental question, we held "1-day Workshop on Quantum Gravity" on July 4, 2019. The talk was very varied. First, Yokokura introduced a formulation of black holes as a configuration of quantum fields. Next, Prof. Izumi discussed the relation of S-matrix unitarity and renormalizability in higher-derivative theories. After lunch, Prof. Ho developed a general discussion of the relationship between dynamical horizon and negative energy. Prof. Yoneya began with the origin of Nambu dynamics and introduced an attempt to quantize it with a Hamilton-Jacobi method. Prof. Matsuo discussed M-theory and a mathematical structure behind it. Finally, Prof. Kawai developed a simple model of how the weak scale comes out of the Planck scale. In addition, there was more applications than expected, and the room was a little small. However, the discussion in the physically dense venue was very active as if a concert in a small venue had a stronger feeling of live, and it was a wonderful conference where the enthusiasm of the speakers could be felt directly. And the participants were in a wide range of fields such as elementary particles, relativity and mathematical physics, and over a very wide range of generations, including master's first grader and retired professor. In this way, it was also very meaningful that active discussions were conducted across fields and generations. Now is the time to study quantum gravity with free ideas.
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2019-07-18
Hot Topic
Workshop on Sine-square deformation and related topics 2019
On July 11th, the workshop entitled "Sine-Square Deformation and related topics 2019," was held at RIKEN Wako Campus. Sine-square deformation (SSD) is a new type of boundary condition at which the coupling constant of the system is spatially modulated. Since its inception, SSD has been studied in various contexts including string theory, condensed matter physics, and quantum field theory. This workshop is the sequel to the workshop previously held at RIKEN two years ago. This time, virtually all the researchers who are actively contributing to the subject attended the workshop.
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2019-07-18
Seminar Report
Report of iTHEMS colloquium - Spacetime Geometry of Black Holes, Wormholes, and Time Machines
General relativity tells us how spacetime is curved by energy distribution and how matter moves in the spacetime. Classical black hole, which is a solution of the classical Einstein equation, has the event horizon and singularity. Event horizon, from which anything cannot escape, is defined at infinite future, and physical quantities such as energy density diverge at the singularity. These properties are not physically acceptable. Then, what are black holes in our universe? Prof. Pei-Ming Ho (National Taiwan University) addressed this question by studying quantum effects in general relativity. The key is the nature of the vacuum. Classical matter always has positive energy, but in quantum field theory the expectation value of energy density can be negative due to quantum fluctuation of the vacuum. The semi-classical Einstein equation connects the expectation value of energy-momentum tensor to the curvature of spacetime. If there is negative energy, traversable wormhole solutions can be constructed. They could be used as time machines for backward time travel, but they would lead to several paradoxes like “Grandfather paradox”. Prof. Ho explained this topic by showing how SF movies were inconsistent with physical laws. Then, he asked “What are the appropriate energy conditions to avoid inconsistencies?” The answer is still unknown, but it should be related to so-called “information paradox” in black holes. Suppose that a star (classical matter) collapses to a classical black hole. Hawking derived that the black hole evaporates slowly by emitting radiations due to the quantum properties of the vacuum. Then, where has the information of the matter gone after the evaporation? The information seems to disappear because the matter is trapped inside the horizon while the black hole evaporates. Any information must be preserved in quantum theory, but the mechanism is not clear in the black hole evaporation. As he said, one scenario is that some remnant is formed instead of complete evaporation. He first explained that, due to quantum fluctuation of the vacuum, the region near the would-be horizon is modified to obtain a “neck” structure without a horizon. The (proper) volume inside the neck is larger than the usual volume of the 3-dimensional sphere with the radius of the neck (because of negative energy). This is like a SF apartment: when you enter a room, it has a larger space than you expected from the outside. This is one possibility of quantum black holes. He also discussed dynamics of the neck black hole. As it evaporates, the neck would shrink and the information inside the neck would be left as a remnant, but this seems to be not a good solution to the information problem because the information would be isolated from the exterior world forever. Finally, he introduced his recent progress: when a trapping horizon (a local and dynamical notion of horizons) becomes timelike, negative energy occurs and the black-hole mass decreases (not by Hawking radiation). It is a non-perturbative effect w.r.t. Planck constant, which could not exist in the classical limit. This result implies that the four factors are closely related: dynamics near quantum black hole, appropriate energy condition including quantum effects, a more proper description beyond the semi-classical one, and the mechanism of information recovery. His entertaining talk showed that a black hole is not just a hole but a window to a new world. It is time to ask again “What is black hole?”
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2019-07-16
Featured Paper of the Week
The KO-valued spectral flow for skew-adjoint Fredholm operators
Spectral flow measures the number of eigenvalue crossings of continuous paths of Fredholm operators (which have finite-dimensional kernels). Atiyah, Patodi and Singer first defined spectral flow as a way to study index theory for odd dimensional manifolds. Recent applications of index theory to topological phases, where anti-linear symmetries may occur, have motivated the study of spectral flow on real Hilbert spaces. The paper develops a theory of spectral flow for skew-adjoint Fredholm operators on real Hilbert spaces, which are a classifying space for KO-theory. Our construction applies to bounded and unbounded Fredholm operators, possibly with additional Clifford symmetries, and generalises all previous notions of analytic spectral flow. The results are also relevant to free-fermionic topological phases, where the topological obstruction to two symmetric Hamiltonians having the same strong topological phase can be exactly measured by the KO-valued spectral flow.
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2019-07-15
Hot Topic
RIKEN-OIST mini Workshop 2019 "Mathematical Condensed Matter Physics" was held on July 5-6, 2019
From July 5 to July 6, RIKEN-OIST mini Workshop 2019, Mathematical Condensed Matter Physics, was held at OIST. We had three excellent lectures and three interesting talks. Prof. Shinobu Hikami gave a lecture about applications of random unitary theory to physics, Dr. Yuta Sekino explained the applications of operator product expansions to non-relativistic theories and Mr. Takuya Furusawa reviewed about dualities in three dimensions. In three talks, Dr. Hidehiko Shimada explained his recent progresses about the four point function in a non-relativistic theory, Dr. Wenliang Li explained recent progresses of conformal blocks, and Mr. Arkaprava Mukherjee reviewed his current achievement. The participants are grateful to the staff of OIST as well as to the iTHEMS assistants for the great help to organize the workshop.
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2019-07-10
Hot Topic
SOKENDAI-iTHEMS Joint Workshop was held from July 7 to July 8
SOKENDAI-iTHEMS Joint Workshop "Genetics meets Mathematics" was held at Hayama, Kanagawa (close to SOKENDAI Hayama campus) from July 7 to July 8. This workshop brought together 36 participants, including 10 from RIKEN and 7 from SOKENDAI, of a wide variety of scientific background such as pure mathematicians, physicists, and biologists. There were lectures and talks on topics related to genetics and evolution given by biologists aimed at mathematicians and physicists without any background in biology, and those by mathematicians and physicists tackling biological problems. It was a very successful "interdisciplinary" event that provided many young mathematicians and physicists a unique opportunity to interact with biologists and vice-versa.
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2019-07-09
Featured Paper of the Week
Instantons in Chiral Magnets
More than 50 years ago, Russian physicist Dzyaloshinsky has proposed the specific interaction in some kinds of magnets to explain weak ferromagnetic behavior of them, and soon after that, Professor Moriya has identified its microscopic origin as the spin-orbit coupling. That interaction, now called the Dzyaloshinskii–Moriya (DM) interaction, is one of the most important topics in both experimental and theoretical study of magnetism. This is because it induces novel inhomogeneously ordered states in spin systems such as a chiral soliton lattice and Skyrmion crystal. These interesting states support non-vanishing "topological" charges and have been experimentally observed in some magnetic materials. In this paper, focussing on one-dimensional antiferromagnetic spin chains with the DM interaction, we exhaustively construct instanton solutions with topological excitations and elucidate their properties based on the field theoretical (nonlinear sigma model) description of spin chains. As shown in Fig, the resulting spin configurations show helical ordering due to the DM interaction.
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2019-07-04
Seminar Report
Math seminar by Hiroki Kodama
Hiroki Kodama had a seminar talk in the iTHEMS math seminar on 20 June. The topic was the foundation of metric space and its generalizations. Metric space is one of the most primitive setting of geometry. This notion is defined in an abstract way by metric function satisfying 3 axioms. Not only the Euclidean metric, which is familiar for all of us, many ideas arising all over the science (e.g. the distance of two DNAs) are formulated as a kind of metric. A main interest of this seminar was a generalization of metric space, which is less popular even for mathematicians. A function satisfying the axioms of metric space except for the symmetry axiom d(x,y)=d(y,x) is called an asymmetric metric (a typical example is the cost for a ship on a river to move from one point to another). In the first half of the talk, Kodama introduced the basic notion of (asymmetric) metric spaces with various examples. In the second half, he introduced an interest of asymmetric metric space by showing rich information it includes.
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2019-07-04
Featured Paper of the Week
Rigidity of the mod 2 families Seiberg-Witten invariants and topology of families of spin 4-manifolds
After the early 1980s, gauge theory has been used by mathematicians to study 4-dimensional spaces (manifolds). The hottest mathematical subject studied by gauge theory is a sort of difference between the shape of topological (continuous) 4-dimensional manifold and that of smooth 4-dimensional manifold. On the other hand, in most of mathematical areas, it is quite significant to understand symmetry of a given mathematical object, such as a manifold. However, about the space of all symmetries of a 4-dimensional manifold, only few things have been known. In this paper, we study the spaces of symmetries of 4-dimensional manifolds. We revealed that gauge theory (more precisely Seiberg-Witten theory) can extract some difference between the shape of the space of symmetries of a topological 4-dimensional manifold and that of a smooth 4-dimensional manifold. In addition to gauge theory, we also used some classical but deep results in higher-dimensional topology invented 50 years ago. Such a combination of gauge theory with classical results in topology is also a new and interesting direction of this paper.
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2019-06-28
AnnouncementWeb page of iTHEMS QCoIn WG has launched.
The web page of iTHEMS QCoIn (Quantum Computation and Information) working group has launched. QCoIn Seminars/workshops, lecture slides and other information are posted there. Feel free to visit the site.
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2019-06-26
Award
Akinori Tanaka received particle physics medal
Our iTHEMS member, Dr. Akinori Tanaka (AIP/iTHEMS) together with Dr. Akio Tomiya (RIKEN BNL Research Center) have received "14th Particle Physics Medal: Young Scientist Award in Theoretical Particle Physics” from Japan Particle and Nuclear Theory Forum. They were awarded in recognition of their recent paper: Akinori Tanaka, Akio Tomiya “Detection of Phase Transition via Convolutional Neural Networks,” J. Phys. Soc. Jpn. 86, 063001 (2017). The citation reads: This paper answers the important question of whether machine learning can capture the existence of phase transition. In this study, in the classical Ising model, spin configurations at various temperatures are generated, and pairs of (configuration, temperature) are used as data. A convolutional neural network is prepared, input data is set, output data is temperature, and machine learning is performed to predict the temperature from the configuration. In the obtained neural network, when the weight of the network connecting the final layer and the layer immediately before it is plotted as a heat map, it can be seen that a large change occurs near the phase transition temperature. This is evidence that machine learning has captured a phase transition. This paper, which shows that machine learning can not only reproduce and use known concepts but also extract the physical concept of phase transition point, is very original and links the subsequent physics and machine learning It made one of the foundations of research. From these facts, we consider this paper to be an award-winning paper. (The above citation was translated from the original in Japanese by use of Google Translation, in order to demonstrate the recent development of Machine Learning) Congratulations, Akinori and Akio!
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2019-06-22
Book
Deep Learning and Physics: From Foundation to Application
Author: Akinori Tanaka, Akio Tomiya and Koji Hashimoto Language: Japanese
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2019-06-20
Seminar Report
Seminar by Dr. Allard van Marle from UNIST in Shouth Korea
Dr. Allard Jan van Marle visited ABBL and iTHEMS this week from his home institute of UNIST in South Korea. On Monday, June 17, he gave a seminar about his work in astrophysics, on particle acceleration and particle-shock interactions. This is a very difficult topic to study because of the very different scales (length, time, and energy) involved. Low-energy electrons and ions create the magnetic field turbulence that lets particle acceleration take place, so numerical simulations should resolve their motion. But accelerated particles have energies orders of magnitude higher, which means the numerical grid must be much larger to track them. Dr. van Marle presented a new numerical method that partially resolves this tension. This "particle in [MHD] cell" code averages out the majority of the low-energy electrons/ions, freeing up computational resources to track the higher-energy particles that are of more interest to most astrophysicists. Shock fronts are everywhere in the universe, but they come in a large variety of speeds, sizes, and locations. The work presented by Dr. van Marle will help to determine how (or if) all of these different shocks behave as natural particle accelerators.
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2019-06-13
Seminar Report
Seminar by RIKEN researcher, Dr. Nathan Shammah
RIKEN researcher Nathan Shammah gave the first seminar for the QuCoIn (Quantum Computing and Information Science) working group. On June 13, he hosted an interactive workshop on open-source software and the Quantum Toolbox in Python (QuTiP) library. Open-source software, which allows anyone to see its source code, is becoming popular in business, in science, and among the general public: even tech giants like Microsoft and Google are investing in open-source projects. Python, in particular, is a highly-developed ecosystem with many packages, and one that most of you are probably already familiar with. The QuTiP code is one such package, which lets you simulate quantum systems, and even quantum circuits, on your (non-quantum) computer. About twenty people attended Nathan’s workshop and started learning to use QuTiP. We hope that this experience, and the new tool kit, will help people to accelerate their research and advance the field. If you have questions about QuTiP, please ask Nathan—he is very happy to discuss the software! And if you are interested in quantum tech research highlights, you can subscribe to Nathan's monthly newsletter on quantum technologies from the link below.
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2019-06-13
Featured Paper of the Week
Probing localization and quantum geometry by spectroscopy
Localization has been one of the main topics of interest in condensed matter physics for more than half a century. Study of localizatoin has recently been entering into a new stage because of the developments in the concept of many-body localization, and also of the recent advances in the technology of quantum-engineered systems such as ultracold atoms and trapped ions. In this paper, we propose a novel method to quantitatively study localization of a quantum state in the platform of quantum-engineered systems. Our proposal makes use of the fluctuation-dissipation theorem; we consider periodically modulating the quantum system and observing the exciation rate. We find that the localization of a quantum state is related to the integral of the excitation rate over the modulation frequency. Our proposal to probe localization does not require high resolutino microscopes to spatially resolve the quantum state. We apply our method to various examples which are of direct experimental relevance in ultracold atoms. Moreover, inspired by a relation between quantum fluctuations and the quantum metric, we describe how our scheme can be generalized to extract the full quantum-geometric tensor of many-body systems. The figure (left) shows how the wavefunction of two interacting particles in a harmonic trap spreads as one increases the interaction, and the figure (right) shows how such spreading can be probed through excitation rate measurements for various values of the interaction strengths.
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2019-06-07
Seminar Report
Seminar by Professor Yasunori Nomura from Berkeley
Prof. Yasunori Nomura from Berkeley Center for Theoretical Physics, for which Prof. Nomura serves as the director, gave a seminar entitled " Quantum Mechanics of an Evaporating Black Hole" on June 6th. In his talk, he elucidated the so-called information paradox of evaporating black holes and plainly presented his resolution of this long-standing paradox. We are particularly pleased that we could invite Prof. Nomura not long after Coordinator Tada's own seminar at Berkeley. Frequent mutual visit between Berkeley and RIKEN would be most beneficial to iTHEMS, so we encourage all the iTHEMS members to find an opportunity to visit Berkeley, or invite somebody from there.
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2019-06-05
Hot Topic
The Journalist in Residence Workshop 2019 was held from May 31 to June 3
From May 31 to June 3, Journalist in Residence Workshop 2019 was held at Tambara Institute of Mathematical Sciences of the University of Tokyo. As for the "Journalist in Residence (JIR)" program in Mathematics and the Journalist in Residence Workshop please look at iTHEMS Newsletter vol 10. This year, there were 11 journalists and 10 participants from RIKEN, 3 from universities and 6 from others. 8 iTHEMS members mainly explained their working field and recent important achievements to the nonspecialists. There were 25 talks in a variety of fields. They were very interesting but the schedule was a little tight. The discussion among the participants continued with joy until very late in the evening as usual. The participants are grateful to the staff of Tambara Institute as well as to the iTHEMS assistants for the great help to organize the workshop.
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2019-05-31
Hot Topic
Introduction to Black Hole Shadow of M87 by Dr. Yosuke Mizuno
On 24 May (Fri.), Dr. Yosuke Mizuno (Frankfurt U.) visited iTHEMS and gave a 15min talk at iTHEMS coffee meeting. Dr. Yosuke Mizuno is a core member of the Event Horizon Telescope (EHT) project to observe “Black Hole Shadow”. He is a core author of the paper V (theory part) of the first detection of the black hole shadow of M87, which was press-released in the world on 10 April, 2019. In the 15 min talk, Dr. Yosuke Mizuno explained why the black hole shadow is expected from Einstein’s Theory for General Relativity. He also introduced the angular resolution of EHT, which was expected to be smaller than angular size of the black hole shadow of M87. After great efforts of the EHT collaboration, finally the EHT collaboration succeeded to take images of the black hole shadow of M87. This was a big discovery, which confirmed the existence of a Black Hole (independently from gravitational waves), mass of the black hole of M87 (about 6 billion solar mass), and the theory of general relativity. For future works, he introduced some unsolved problems such as confirmation of rotation of the black hole of M87, mechanism of jet formation of M87, and possible correction of Einstein’s theory of general relativity. After the talk, “endless” Q&A was followed between Dr. Yosuke Mizuno many iTHEMS members.
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2019-05-28
Featured Paper of the Week
Uncovering critical properties of the human respiratory syncytial virus by combining in vitro assays and in silico analyses
When a virion is left in a liquid medium over some time, it loses its ability to infect cells. This is often because the virion surface proteins become deformed, e.g. because of heat or the ionic content of the medium, such that they can no longer effectively bind cells and infect them. For many viruses (e.g. influenza, HIV and hepatitis C) this loss of infectivity over time follows an exponential. In this paper, we evaluated the rate at which the respiratory syncytial virus (RSV) loses infectivity over time. We were surprised when we found that the loss of infectivity of RSV in our data did not follow an exponential. We used a Weibull distribution to describe the decay and estimated its shape parameter to be k=0.30 [95% credible region: 0.27-0.36], which means the rate of decay gets smaller over time. This is typical of a bad production system wherein a lot of defective products are made which fail soon after production, leaving only well-made products which become defective at a lower rate. In a 2013 paper, Liljeroos and others (doi: 10.1073/pnas.1309070110) showed that as RSV buds from the surface of the cell, bud pinching (closing the bud to free the virion from the cell) is physically difficult, and often leads to misformed buds. The bad structure leads the filamentous (worm-shaped) RSV bud to “plop” outwards (become spherical), flip its surface F proteins (responsible for RSV attachment to host cells) from their pre-trigger (very infectious) to their post-trigger (poorly infectious) state. This is consistent with our finding of k<1, wherein RSV that don’t pinch their bud properly upon cell exit fail (lose infectivity) very early on, and the remaining RSV population which pinched properly will decay following a much less steep exponential.
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2019-05-23
Seminar Report
Report of iTHEMS Special Lecture – How did the Universe Begin? -Inflation Theory & Road to the Proof-
On May 21st, iTHEMS Special Lecture by Dr. Katsuhiko Sato (Professor Emeritus, The University of Tokyo / Director, Research Center for Science Systems, Japan Society for the Promotion of Science) was given at Okochi Hall for more than 100 participants. Dr. Katsuhiko Sato is well known as a scientist who discovered the inflation mechanism of the early Universe in 1981. In the special lecture, Dr. Katsuhiko Sato gave an introduction about the expansion of the universe, mysteries about uniformity & isotropy of the universe, and absense of monopoles. Then Dr. Katsuhiko Sato explained how he got an idea of the inflation mechanism, motivated by Spontaneous-Symmetry-Breaking (SSB) mechanism (SSB was proposed by Dr. Yoichiro Nambu), and explained how these problems are solved by the Inflation mechanism. Dr. Katsuhiko Sato introduced about future missions that will prove firmly the inflation mechanism, including LiteBIRD that will measure B-mode in the polarization of cosmic microwave background in the universe. It was a great coincidence that JAXA announced on the same day, May 21st, that JAXA has made a decision to launch LiteBIRD. We wish the Inflation mechanism proposed by Dr. Katsuhiko Sato will be proved firmly in the near future.
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2019-05-18
Person of the Week
Self-introduction: Keita Mikami
I am Keita Mikami, a research scientist at iTHEMS. My research field is partial differential equations and I work on linear Schrödinger equation. Main subject in the research of linear Schrödinger equation is its spectrum. I have studied localization in direction phenomena of Schrödinger operators with homogeneous potentials of order zero. Roughly speaking, this is a phenomena such that a solution to Schrödinger equation with this class of potentials localizes in direction as time goes to infinity. I have used spectral theory and semiclassical(microlocal) analysis to understand this phenomena and its application. Though my interest comes from mathematics, I want to understand physical aspects of Schrödinger equations and find some application of my results in physics since Schrödinger equation is the governing equation in quantum mechanics.
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2019-05-16
Hot Topic
The First Coffee Meeting Talk in Reiwa Era (Dr.Nagisa Hiroshima)
The first 15 min. coffee meeting talk in Reiwa era was given by Nagisa Hiroshima on May 10. She explained how to extract the density distribution of dark matter from observation.
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2019-05-16
Seminar Report
Dr. Shunji Matsuura from 1QBit gave a series of lectures
Our visitor Dr. Shunji Matsuura from 1QBit, a startup company specializes in quantum computing and quantum information technology based in Vancouver, Canada gave a series of lectures from May 13 (Mon) through May 15 (Wed). Dr. Matsuura started with a basic explanation of qubits and their entanglement. Then, he moved on to explain various method employed in the field of quantum computing, such as Variational Quantum Eigensolver (VQE). His explanation was especially clear to physicists, since Dr. Matsuura’s background is string theory receiving his Ph.D. in string theory from the Perimeter Institute for Theoretical Physics and the University of Tokyo, and he used to conduct research at the Kavli Institute for Theoretical Physics (University of California, Santa Barbara), McGill University, Riken, YITP (Kyoto University), and the Niels Bohr Institute (University of Copenhagen). His current research focuses on the fundamental aspects of quantum-enhanced optimization, such as error correction and speedup, which are also of interest to some iTHEMS members, and we are hoping a lot of fruitful collaborations between iTHEMS and Dr. Matsuura as well as 1QBit group in future.
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2019-05-15
Research News
Masaru Hongo was highlighted in a recent article of RIKEN RESEARCH "Describing the early Universe by simplifying complicated equations"
A powerful mathematical method for simplifying the analysis of highly complex systems has been extended by a RIKEN-led team. This will enhance its usefulness for researchers in a wide range of fields.
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2019-05-15
Featured Paper of the Week
Comments on holographic entanglements in cutoff AdS
AdS/CFT correspondence tells us that a gravity in AdS space is equivalent to CFT which lives on the boundary of the AdS. Recently it has been proposed that an integrable TT deformation of CFTs produces a deformed AdS/CFT. According to the conjecture, the AdS boundary is located at a finite radial cutoff. To investigate the deformed correspondence, we studied holographic entanglement entropy in the cutoff AdS, which is well known as a probe of information theoretic quantity. In particular, we explored its phase transitions. For two-interval entanglement entropy, the transition point monotonically decreases with a deformation parameter, which means that by the TT deformation the degrees of freedom in subsystems are decreasing. Our result implies that the effect of the TT deformation can be regarded as the rescaling of the energy scale.
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2019-05-11
Person of the Week
Self-introduction: Kanato Goto
My name is Kanato Goto and I have been working at iTHEMS since April 2019. I am a theoretical physicist studying string theory and my main research interests lie in foundational questions about quantum gravity, black hole physics, and supersymmetric quantum field theories. I am currently trying to understand the basic mechanism and the mysteries of the holographic principle, which states that information about gravity and the spacetime contained in our three-dimensional universe can be completely described by the two-dimensional boundary surrounding it, just like a hologram emerges from a sheet of photographic film. At iTHEMS, I hope to broaden my research horizon through discussions with researchers in various fields.
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2019-05-09
Hot Topic
Visiting Berkeley
Tsukasa Tada, the coordinator of iTHEMS, has visited SUURI-COOL Berkeley, last week. During his stay, Tada gave a seminar at the Berkeley Center for Theoretical Physics, which is one of the best group dedicated to particle physics and string theory. He also enjoyed the reunion with three iTHEMS members stationed at Berkeley, Takashi Okada, Jason Chang, and Masahiro Nozaki. All of them were having a great time at Berkeley. We strongly encourage iTHEMS members to visit SUURI-COOL Berkeley and take advantage of the prestigious environment of the University of California, Berkeley, and the Lawrence Berkeley National Laboratory.
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2019-05-09
Seminar Report
Report of iTHEMS colloquium - Quantum computing: current status and prospects
On April 25th, iTHEMS Colloquium featured Prof. Keisuke Fujii from Osaka University. Prof. Fujii has just moved to Osaka and started his laboratory for Quantum computing. Started with quoting Richard Feynman and went on to summarize the history of quantum computing. Then he gave a pedagogical explanation of the principle of quantum computing and the overview of the subject. Next, among over three hundred papers at Quantum Algorithm Zoo, he singled out Quantum Phase estimation as the most important Algorithm. Prof. Fujii explained the algorithm and told the audience that it has application to Prime factorization, Quantum Chemistry and Quantum simulation as well as Quantum linger system solver, which has relevance to AI. He then gave the assessment of the current status of quantum computing and future prospect. The lecture was concluded by the exposition of Quantum-classical hybrid algorithm and its application to machine learning. Because of the exciting topic featured, the lecture attracted many keen audience.
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2019-05-08
Research News
Masaru Hongo and Tatsuhiro Misumi were highlighted in a recent article of RIKEN RESEARCH "A smaller spin system yields its phase diagram"
By employing a clever approximation, three theoretical physicists at RIKEN (Masaru Hongo and Tatsuhiro Misumi of the iTHEMS and Yuya Tanizaki of the RIKEN BNL Research Center) have calculated the phase diagram for an extension of a system proposed over 30 years ago. In addition to advancing the theory of condensed matter physics, this finding could have practical implications for systems made up of particles with the quantum property of spin. This research highlighted in a recent article of RIKEN RESEARCH.
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2019-05-08
Research News
Review on synthetic dimensions published in Nature Reviews Physics
Nature Reviews Physics is a new journal, just launched this year, focusing on publishing reviews in the area of physics. Dr. Tomoki Ozawa (iTHEMS Senior Research Scientist) together with Dr. Hannah M. Price (University of Birmingham, UK) wrote a review for Nature Reviews Physics on “synthetic dimension,” which is a recently emerging method for simulating high dimensional models using low dimensional platforms making use of non-spatial degrees of freedom as effective dimensions. The review summarizes the current status of the research of synthetic dimensions with a focus on atomic, molecular, and optical physics, where the method is most actively studied. A figure from the review is also adapted for the cover of the May 2019 issue of Nature Reviews Physics.
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2019-04-26
Person of the Week
Self-introduction: Kenta Sato
Hello, I am Kenta Sato. My major is mathematics, in particular algebraic geometry. In algebraic geometry, we study algebraic varieties, which are defined as the zero sets of polynomial equations. When you hear polynomials, you may imagine polynomials whose coefficients are integers, rational numbers, or complex numbers. But, it sometimes important to consider polynomials whose coefficients are in some other field, for example a field with positive characteristic. I have been studying polynomials, rings and algebraic varieties over a field with positive characteristic. In particular, I am interested in F-singularities and globally F-regular varieties, which are defined in terms of positive characteristic methods. I also hope to find some application of positive characteristic methods to problems in mathematics and other areas.
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2019-04-26
Announcement
Lectures on Quantum Computing by Dr. Shunji Matsuura
Dr. Shunji Matsuura will visit iTHEMS to give a series of lectures on Quantum Computing. The lectures will be held from May 13 (Mon.) through May 15 (Wed.) in Wako Campus, RIKEN. The details will be announced later. Shunji received his Ph.D in string theory from the Perimeter Institute for Theoretical Physics and the University of Tokyo. Previously, he was a member of the Kavli Institute for Theoretical Physics (University of California, Santa Barbara), McGill University, Riken, YITP (Kyoto University), and the Niels Bohr Institute (University of Copenhagen). Shunji's current research focuses on the fundamental aspects of quantum-enhanced optimization, such as error correction and speedup.
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2019-04-25
Hot Topic
Virtual reality a huge success at RIKEN Open Day
At RIKEN’s Open Day, ABBL and iTHEMS members joined together to let residents of Wako (and beyond) explore astrophysics data using virtual reality. The demo, developed by Gilles Ferrand, had two major components. In one, visitors could watch as a supernova remnant expanded, compressing 500 years of evolution to just 10 seconds (and sweeping up the visitors if they were standing in the right spot!). In the second, guests could explore the chemical composition resulting from a thermonuclear explosion (a.k.a. Type Ia supernova), looking at how elements from carbon to iron formed complex structures; identifying similar structures in supernova remnants (hundreds or thousands of years later) may offer clues to how the supernovae occurred. Importantly, the demo was not just pretty pictures for the public to look at (though it certainly was pretty). The guests got to enjoy actual scientific data, which was published in real academic journals. And there was a lot of interest in the demo: about 160 people tried out the demo on two headsets. Many more tried to get tickets for a VR experience (Gilles’ conservative estimate is that 400-500 people visited the demo room; Don Warren’s more optimistic guess is more than 600). There is clearly an appetite for exciting visualizations of scientific data. If you want to explore the demo yourself, send Gilles or Don an email. Many people in ABBL and iTHEMS contributed to make the VR booth a success. If you want to join us and help make next year’s event even better, we welcome the support!
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2019-04-25
Seminar Report
iTHEMS public lectures at RIKEN Open Day
iTHEMS public lectures at the RIKEN open day on April 20, 2019, were held with an extreme success. The lectures are (1) Surprising Theorem of Gauss (Y. Kubota), (2) Mystery of Circadian Rhythm (G. Kurosawa), (3) Mechanism of Artificial Intelligence (M. Taki), (4) Coldest Place in the Universe (T. Ozawa), (5) What is Dark Matter ? (N. Hiroshima), (6) Evolution through Copy and Paste of DNA (J. Fawcett). Thank you all who have contributed to make this happen!
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2019-04-24
Seminar Report
Report on ZetaValue2019 Conference by Chacha (Dr. Ade Irma Suriajaya)
The conference "Value Distribution of Zeta and L-functions and Related Topics" has successfully ended on March 27, 2019. The whole conference program started with a colloquium, ZetaValue2019-iTHEMS Special Mathematics Colloquium, on March 21, followed by the main conference held from March 22 to 26, and concluded with a one day workshop on March 27. We had more than 120 participants in total, among we had over 100 number theorists and overall about 111 mathematicians. We managed to gather people from over 20 different countries, and more precisely there were 50 participants coming from overseas from 40 different institutions. Number theorists from over 30 different institutions in Japan also took part in the conference. As far as we, the organizers, know, this is very rare achievement for a math conference in Japan; at least in analytic number theory field, this was the first ever conference in Japan to gather this many people coming from various places. We had 2 invited colloquium talks, 14 invited plenary talks, 9 contributed short talks, 15 contributed poster talks (excluding mine), and 9 contributed workshop talks. I would like to thank iTHEMS members and a few other RIKEN scientists who attended the colloquium. I hope that the talks were interesting enough and I really hope to maintain this communication and even boost our interdisciplinary connection further. Finally, the most important thing I would like to address here is: I deeply thank iTHEMS, and further, RIKEN who supported and assisted this conference, who made all of this possible. Thank you very much!! To all the assistants who helped me a lot from the preparation until the concluding process, please accept my sincere gratitude.
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2019-04-24
Person of the Week
Self-introduction: Hiroshi Yokota
I am Hiroshi Yokota, a physicist, who have joined iTHEMS since April, 2019. For 5 years, I have investigated a polymer physics, especially, theoretical framework of polymer crystallization. The polymer is a string-like large molecules whose characteristics play important roles in crystallization process. In contrast to the conventional crystal such as metals, the polymer crystal is a solid composed of crystal and amorphous regions due to the characteristics of the string-like molecules, where the polymer crystal is applied to production of industrial products, for example, films and threads (stuff of our clothes). In iTHEMS, by using the knowledge of polymer crystallization and of theoretical treatments of the polymer chain, I will investigate biophysics, especially, dynamics of the formation of the chromosomes.
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2019-04-18
Hot Topic
iTHEMS Starter Meeting for FY 2019 on April 12, 2019
In Japan, April is the time for a fresh start blessed by cherry blossoms. On April 12th, we held the annual iTHEMS Starter Meeting. It was an occasion for us to welcome new members. At the meeting, Program Director Hatsuda’s greeting was followed by one minutes self-introduction by the members present. We hope we have another fruitful fiscal year ahead. The slides used at the meeting including the self-introduction is available at the link shown below.
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2019-04-15
Person of the Week
Self-introduction: Takuya Sugiura
My name is Takuya Sugiura and I have been working at iTHEMS/RIKEN since April 2019. My main interest is on theoretical hadron physics, including interactions between hadrons, exotic hadrons, and heavy-quark systems. I am currently working on lattice QCD calculations of hadron interactions. Here at RIKEN I hope to see people from many different backgrounds; this will be a great opportunity to broaden my knowledge and scientific views.
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2019-04-12
Hot Topic
Fruitful Exchange Across the Disciplines: iTHEMS-AIMR Joint Workshop "Medicine meets Mathematics"
A truly interdisciplinary workshop was held at Tohoku University, as a joint workshop of iTHEMS and AIMR, Tohoku Univ. on March 29th. The workshop was veritably entitled “Medicine Meets Mathematics,” where about half the speakers were Medical doctors and the rest was mathematicians and theoretical physicists. At the workshop, lively discussions were taken place and a lot of fruitful exchange across the disciplines were made. The workshop was so successful that we are planning the next workshop in a larger scale.
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2019-04-11
Press Release
Observation of Quantized Heating Rate in Ultracold Topological Matter
An international collaboration of researchers from University of Hamburg, Université libre de Bruxelles, and RIKEN iTHEMS observed quantized heating rate, demonstrating a novel universal probe for topological states of matter. The experiment was performed using a gas of ultracold potassium atoms. The researchers looked for the difference in heating rate upong "shaking" the system clock-wise and counter-clock-wise, and confirmed that this different is quantized to the value of the "Chern number" of the system, a topological invariant characterizing a two-dimensional system. The experiment took place in Hamburg, with theoretical collaborations from theorists in Bruxelles and RIKEN iTHEMS.
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2019-04-10
Award
Commendation for Science and Technology by MEXT
Prof. Hiroshi Suito (AIMR/iTHEMS) has received the Commendation for Science and Technology by MEXT : Prizes for Science and Technology. Citation is 数学を用いた大動脈病態メカニズムの解明に関する研究 Research on the elucidation of the aortic pathogenesis mechanism using mathematics Many congratulations, Hiroshi !
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2019-04-05
Person of the Week
Self-introduction: Nagisa Hiroshima
Hello, I am Nagisa Hiroshima. I have joined the iTHEMS from April 2019. My research interest covers varieties of topics in the Universe such as dark matter, structures of galaxies, and gamma-ray emitting objects. I am now working on dark matter search in the Universe with gamma-ray observations combining theoretical methods. I would like to have lots of daily discussions and to try much wider topics here.
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2019-04-04
Person of the Week
Self-introduction: Hokuto Konno
I have been working in the mathematical study of gauge theory. In particular, I have developed Seiberg-Witten theory and Yang-Mills theory for families of 4-dimensional manifolds, and used them to examine the topology and geometry of such families. One of typical objects studied using gauge theory for families is the space consisting of all symmetries of a given 4-dimensional manifold. The space of symmetries is a natural mathematical object, but at the same time, this space is an infinite-dimensional complicated space in general, and consequently quite hard to attack. Interestingly, some of my recent work with several groups revealed that we can extract information about the space of symmetries of some 4-dimensional manifolds using gauge theory for families. I am trying to go ahead with this direction, and also to develop other aspects of gauge theory, relating to a sort of topological quantum field theory.
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2019-04-03
Press Release
Researchers pinpoint origin of photons in mysterious gamma-ray bursts
Scientists from the RIKEN Cluster for Pioneering Research and collaborators have used simulations to show that the photons emitted by long gamma-ray bursts—one of the most energetic events to take place in the universe—originate in the photosphere—the visible portion of the “relativistic jet” that is emitted by exploding stars.
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2019-04-01
Research News
Review on Topological Photonics published in RMP
A team of physicists led by Dr. Tomoki Ozawa (iTHEMS Senior Research Scientist) published a review article titled "Topological photonics" in Reviews of Modern Physics. Study of topological phases of matter started in solid-state physics through the discovery of the quantum Hall effect. However, it has been recognized during the past decade that topological band structures, which are at the heart of the phenomenon of the integer quantum Hall effect, are general properties of waves inside medium, and thus are much more ubiquitous. One of the most active fields outside solid-state electron systems where topological physics has been studied is photonics. This review summarizes the current status of the study of topological band structures and topological phases of matter in photonics and related fields. The review is authored by an international collaboration of eleven scientists including both theoretical and experimental researchers from eight different countries.
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2019-04-01
Hot Topic
RIKEN's community newsletter features Dr. Jason Chang at SUURI-COOL (Berkeley)
Jason Chang (iTHEMS Research Scientist in LBNL) was featured in the RIKEN's community newsletter, RIKENETIC. He talks about exciting challenges and opportunities in San Francisco Bay Area. Worth reading!
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2019-03-27
Hot TopicCongratulations on new positions, farewell message from Program Director of iTHEMS
This is the last volume of iTHEMS NewsLetter in FY2018. It is our great pleasure that iTHEMS has been so active during this fiscal year. Some of the members will leave iTHEMS. Keisuke Fujii (JSPS Research fellow (DC2)). Shun Furusawa (specially appointed assistant prof., Tokyo Univ. of Science) Masaru Hongo (specially appointed assistant prof., Keio Univ.) Motoko Kato (specially appointed assistant prof., Ehime Univ.) Masashi Tachikawa (associate prof., Kyoto Univ.), Ade Irma Suriajaya (specially appointed assistant prof., Kyushu Univ.). We congratulate them for new positions and look forward to their further success !
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2019-03-26
Award
Dr. Iritani receives the Best English Presentation Award
Ryosuke Iritani (iTHEMS, Research Scientist) received "the Best English Presentation Award" on March 16, 2019 for his English presentation, When parasites are selected to kill the young, at the 66th Annual Meeting of the Ecological Society of Japan. Congratulations !
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2019-03-25
Hot Topic
Article of Dr. Ade Irma Suriajaya on RIKEN Research “Making the most of zeros”
Article of Dr. Ade Irma Suriajaya has been posted on RIKEN Research. Please check out the interview on her research life !
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2019-03-22
Hot Topic
The 2nd International Workshop in Vietnam ended successfully
"The 2nd International Workshop on Quantum Many-Body Problems in Particle, Nuclear, and Atomic Physics" was held on March 7-11, 2019 at University of Khanh Hoa (UKH), Nha Trang city, Vietnam. We had 25 talks during the workshop on various topics ranging from quarks, hadrons, nuclei and atoms to neutron stars. Also, public talks by Prof. Akito Arima (former president of RIKEN) on education and science management and by Dr. Nguyen Dinh Dang (RIKEN Nishina Center) on multilayer painting. There were lively discussions among the participants from Japan, Vietnam, India, China and USA. Because of the success of this 2nd meeting, the 3rd workshop in Vietnam is planned on 2021.
118 news in 2019