Session Chair : Hirofumi Tomita (RIKEN R-CCS)

• Satoshi Matsuoka, RIKEN R-CCS

• "Fugaku: Lessons Learned and Directions for the Future"

• After 10 years of R&D by the entire Japanese HPC community headed by Riken and Fujitsu, Fugaku became operational in March 2021. During its almost a year preproduction and now in full operation, Fugaku has met its R&D goals fully, and in fact exceeded the targets, such as much lower power than anticipated in actual production, only nominal power increase over its predecessor K, effectively meeting the DoE goal of "Exascale Machine in 20 MegaWatts". By all means, there are many lessons learned that pave the way for its improvements during its lifetime, as well as for new generations of supercomputers for the future, which will be reflected in the new 'feasibility study' to commence in April, 2022.

Session Chair : Teruki Honma (RIKEN BDR)

• Shinobu Yoshimura, The University of Tokyo

• "Super-simulation of Coal Gasification Facility on Fugaku"

• In this research, we target one of innovative clean energy systems, i.e. carbon-free coal gasification plant. The coal gasification is one of the key technologies to drastically reduce CO2 emission from coal fired power generation. Coal is crushed into fine particulate matter and then partially burned into gas in a high-pressure and elevated-temperature environment.
  We perform a high-fidelity two-way coupled simulation of combustion turbulent flow and thermal conduction and cooling in a reactor vessel of a laboratory-scale coal gasification facility. We first explain our developed multiphysics and multiscale simulations on the Supercomputer Fugaku, which we call Super-simulation in short. Here a unique parallel coupler, REVOCAP_Coupler, is used to integrate highly parallelized independent solvers such as a FVM-based combustion LES flow solver, FFR-Comb, and a FEM-based thermal conduction and cooling solver, ADVENTURE_Thermal.
  The simulation results are quantitatively compared with experimental results obtained from the laboratory-scale experimental facility. We succeeded in quantitatively reproducing the experimental phenomena in the facility with regard to temperature distribution as well as generated chemical components. The developed simulations will be powerful tools to improve the design and operation of actual coal gasification plants.

• Soshi Kawai, Tohoku University

• "Fully-automated high-fidelity scale-resolving simulation around full aircraft configurations"

• This talk describes our recent studies of the next-generation fully-automated high-fidelity scale-resolving flow simulation around full aircraft configurations at flight high Reynolds numbers. The challenges are the (1) fully-automated grid generation around complex full aircraft geometries, (2) near-wall turbulence modeling for the scale-resolving simulation at high Reynolds number, and (3) high-fidelity numerical method for compressible turbulent flows. In this talk, we specifically discuss item (3), our proposed game-changing physically-consistent stable and non-dissipative numerical method for scale-resolving compressible flow simulations, something that existing numerical methods fail to do robustly. Then, an illustrative application to near stall flows around complex full aircraft configurations with high-lift devices using the supercomputer Fugaku is given to show the capability of our numerical framework.

• Atsushi Oshiyama, Nagoya University

• "Computics Approach toward Underlying Science in Semiconductor Power Electronics"

• “Computics” is the word which represents interdisciplinary collaboration between materials science and computer science (http://computics-material.jp/index-e.html). I report such collaboration that enables us to perform accurate-enough large-scale calculations based on quantum theory for various materials exploited in future power electronics. The calculations has been done in the density functional theory (DFT) with either the usual Kohn-Sham scheme or a newly developed Neural-Network-assisted orbital-free scheme. The actual computations are performed with our RSDFT (Real Space DFT) code which is most appropriate for the massively parallel architecture of current supercomputers.
  
  GaN is a premier material in optoelectronics and now emerging in power electronics. This is due to its wide band gap, the robustness under harsh environments, and relatively high carrier mobility. However the quality of its epitaxial thin films and device interfaces are not satisfactory compared with the Si devices, thus being the obstacle to replace the Si technology. I here report the DFT calculations that clarify microscopic mechanisms of GaN epitaxial growth, predict high-quality of the device interfaces with newly explored amorphous Al and Si oxides, and unveil the electronic properties of the complex of the dislocations and acceptor impurities.

Session Chair : Yasumichi Aoki (RIKEN R-CCS)

• Masaki Satoh, The University of Tokyo

• "Large Ensemble Atmospheric and Environmental Prediction for Disaster Prevention and Mitigation"

• Extreme weather events such as typhoons and heavy rainfalls have become increasingly severe in recent years. To realize disaster prevention and mitigation from extreme weather events that cause disasters, we conduct large ensemble weather and atmospheric environment forecasting experiments from a few days to several weeks to seasonal scales using the Supercomputer Fugaku. We conduct high-resolution simulations representing cumulonimbus clouds and mesoscale convective systems in large ensembles. W also developed an advanced assimilation method combined with observation big data with intensive IO connections. As examples, we introduce simulations with an ensemble size of 1,000 for the senjou-kousuitai event (quasi-stationary band-shaped precipitation systems) in Kyushu, July 2020, and Typhoon Faxai in Sep. 2019. We realize innovative numerical weather and atmospheric environment prediction technology for a new era that enables high-resolution numerical weather prediction with probability information.

• Shigeo Wada, Osaka University

• "Development of a whole-brain blood circulation simulator for personalized medicine support"

• Through large-scale computational mechanics simulation using supercomputer Fugaku, we aim to clarify the blood circulation mechanisms at the whole brain level and establish personalized medical support technology that integrates computational analysis and medical data. To achieve this goal, we developed a framework to construct a multiscale human cerebrovasculature model with a hybrid approach using image based geometry and mathematical algorithm. Three-dimensional fluid analysis was performed using a cerebral artery model obtained from 20 subjects. The results showed that there are individual differences in the blood flow direction of the Circle of Willis and the distribution of blood flow to the left and right cerebral arteries. The blood flow distribution ratio to each major artery was similar to the result measured by MRI, and it was found that the vascular tree structure of the cerebral artery itself plays a major role in flow distribution. The computational analysis quantitatively showed the effect of collateral circulation on blood flow recovery during cerebral infarction. Furthermore, we succeeded in preliminary analysis of cerebral microcirculatory analysis including oxygen transport by deformable red blood cells.

Session Chair : Florence Tama (RIKEN R-CCS)

• Yuji Sugita, RIKEN R-CCS

• "Multi-scale simulations of large biological systems on Fugaku"

• Atomistic structures of biomolecules and molecular interactions between them are both important for understanding molecular and cellular functions. Most of biological reactions happen together with slow conformational changes of biomolecules in crowded cellular environments. Therefore, we need to extend the timescales as well as size limitations in molecular simulations without losing their computational accuracy. For this purpose, we aim to develop multi-scale simulation methods in molecular dynamics (MD) software GENESIS, which include atomistic, coarse-grained, and QM/MM models. We have already optimized atomistic MD simulations using GENESIS on Fugaku and many users are utilizing the functions in their simulations on Fugaku. However, coarse-grained MD introduces a large difference of particle densities in each cell (or domain), which requires to develop a new spatial decomposition approach with an efficient load-balance technique in GENESIS. In the talk, we explain newly available atomistic and coarse-grained molecular models in GENESIS and discuss novel computational techniques to parallelize the multi-scale simulations on Fugaku efficiently.

• Junichiro Makino, Kobe University / RIKEN R-CCS

• "Current status of the project "Toward a unified view of the universe: from large scale structures to planets""

• We overview the current status of our project within the Program for Promoting Researches on the Supercomputer Fugaku, Toward a unified view of the universe: from large scale structures to planets. Our aim is to develop simulation codes which achieve high efficiency on Fugaku, for problems of all scales in astrophysics, from large scale structures in the universe to planet formation, solid planet evolution and surface environments of planets. We will showcase some of the achievements and scientific results.

• Makoto Tsubokura, Kobe University / RIKEN R-CCS

• "Digital Transformation of the Manufacturing Process and Smart Design in the Society 5.0 Era."

• In Japan, so-called Society 5.0, following hunting (1.0), agricultural (2.0), industrial (3.0), and information (4.0) societies, was proposed by the government as the future Japan should aspire to. Different from the Society 4.0 where people access a cloud service in cyberspace from the physical space through the Internet, and search for, retrieve, and analyze necessary information or data, in Society 5.0 people, things, and systems are more tightly and organically connected with each other in the cyberspace, and Artificial Intelligence in the cyberspace feedbacks the necessary information in the physical space. In this talk, we will introduce our attempt to realize the smart design of the industrial products on the supercomputer “Fugaku" by tightly coupling the high-performance computing simulation and data science technology. Some topics include “Road vehicle aerodynamic design based on the multi-objective optimization by coupling engineers' and stylists' design space" and “Indoor space design robust against infectious diseases".

• Takahito Nakajima, RIKEN R-CCS

• "Realization of Innovative Light Energy Conversion Materials utilizing the Supercomputer Fugaku"

• In our Fugaku promoting research project, we aim to realize the social implementation of innovative light energy conversion materials using massive materials simulations and informatics on Fugaku. Specifically, we would like to realize hydrogen-generating photocatalysts with the world's highest conversion efficiency of over 10% using Japan-originated technology in collaboration with industries. We would also like to socially implement the photocatalysts that inactivate infectious viruses and selectively and efficiently generate hydrogen peroxide for dis-infection. Furthermore, we would like to realize lead-free perovskite solar cells with a conversion efficiency of over 30% surpassing silicon-based solar cells. In my presentation, I would like to present an overview and several achievements of our project.

"List of Accepted Posters and Session Chairs"

Session Chair : Mitsuhisa Sato (RIKEN R-CCS)

• José Ignacio Latorre, National University of Singapore

• "Variational Quantum Algorithms"

• Classical and quantum computers work together in the class of problems that can be addressed using variational techniques. The quantum circuit is defined by classical parameters, and those provide a search space to solve the problem.
  A short review of some of the ideas involved will be presented.

Session Chair : Toshiyuki Imamura (RIKEN R-CCS)

• Travis Humble, Oak Ridge National Laboratory

• "Scientific Discovery and Innovation with Quantum Simulation"

• Among the advances afforded by quantum information, new methods for modeling and simulation of quantum mechanical systems offer a revolutionary merger between physics and computer science. Many scientific disciplines will benefit from this versatile paradigm to probe the structure and dynamics of quantum matter by accelerating the time-to-solution of simulations and broadening the regime of physical models. Here we present leading techniques for quantum simulation including applications to specific domains, testing and evaluation on current hardware, and the potential to realize quantum computational advantage. We report applications that simulate novel phases of quantum matter using state-of-the-art methods for error mitigation with noisy intermediate-scale quantum devices, and we detail the intermediate goal of integrating quantum processing units with high-performance computing workflows. We highlight the latest efforts of the Quantum Science Center to integrate these techniques and deliver the next-generation of quantum simulation platforms for empowering scientific discovery and innovation.

• Yasunobu Nakamura, RIKEN Center for Quantum Computing

• "Research activities in RIKEN Center for Quantum Computing"

• We launched RIKEN Center for Quantum Computing (RQC) in Apr 2021. In this talk, we will introduce our research activities in RQC. We also discuss our hardware/middleware development efforts focused on superconducting quantum computing.

Session Chair : Masaaki Kondo (RIKEN R-CCS)

• Mitsuhisa Sato, RIKEN R-CCS

• "Programming models for integrating Quantum Computer with "Classic" HPC Systems"

• First of all, the overview of researches related to the technologies of Quantum Computer (QC) in RIKEN R-CCS will be presented. While the QC is promising to break through the limits of the existing computational technologies for several hard problems to solve, it is important to integrate the QC with cutting-edge supercomputers since the QC will not replace all functions of existing high-performance computing technologies. Our group is working on the programming models to integrate the QC with supercomputers such as Fugaku. The global task programming model which enables to offload particular functions to the QC as a task by the remote procedure call (RPC) will be presented as one of such programming models.

• Toshiyuki Imamura, RIKEN R-CCS

• "Contributions to Quantum computing from classical Numerical computing software"

• Before the quantum computer dawns, we have to learn about the behavior of quantum computers and how to implement algorithms by performing various emulations on classical computers. Even after the actual quantum computer becomes available for practical use, it is essential to work with the principle of the classical computer and the classical algorithms.
  
  At R-CCS, we have operated classical supercomputers and have excellent "classical software assets" accumulated during the development process of the K computer, Fugaku, and next-generation systems. Our team's research has been based on the development of numerical libraries. We have been developing methods and software for large-scale eigenvalue calculations for over ten years, which are indispensable for emulating quantum computers and hybrid operation after practical use.
  
  In the symposium presentation, We will report the current status and future research collaborations with quantum computer and classical numerical software, especially eigenvalue and singular value calculations, focusing on some aspects of their relevance to the emulation and hybrid usage of quantum and classical computers.

• Seiji Yunoki, RIKEN R-CCS

• "Quantum computing for quantum many-body systems: variational quantum algorithms and beyond"

• I would like to present some of our research activities on quantum computing for simulating quantum many-body systems [1-5], which has been believed to be one of the most promising applications for quantum computers since R. Feynman first suggested. Considering noisy near-term quantum devices with a relatively small number of qubits, one of the main focuses in the current quantum simulation research is to identify what one can do with such noisy quantum devices that is not too trivial but still interesting. For this purpose, variational quantum algorithms within the quantum-classical hybrid scheme have been most extensively studied with many successes. On the other hand, it has been recognized that there are several sever problems to be solved for achieving scalable simulations. Here, I would like to show some of our attempts to overcome these issues. I will also discuss our current status of developing classical simulators for quantum computing using large scale parallel supercomputers such as Fugaku.

Session Chair : Seiji Yunoki (RIKEN R-CCS)

• Rodney Van Meter, Keio University

• "The Usefulness of Quantum"

• A question on everyone's minds is, when will quantum computers become useful? Will they exceed the performance of large-scale, highly parallel classical supercomputers? In this talk, I will discuss how interference patterns drive quantum algorithms, review some recent results in quantum hardware, then place these concepts in a framework for thinking about the relative strengths of classical and quantum systems.

• Ye Jun, A*STAR

• "Introducing Quantum Computing Research in IHPC, A*STAR: Our Way Towards Practical Quantum Advantage"

• Quantum computers have the potential to produce tremendous improvements in computational performance for a wide range of problems in various fields, including optimisation, machine learning, chemistry, finance, and healthcare. As the performance of quantum hardware improves, so does the possibility of implementing quantum algorithms that outperform their classical counterparts. There is currently an ongoing race amongst various academic research groups, companies, and national research labs to produce the first demonstration of a practical quantum advantage – a milestone in which a quantum computer solves a problem of practical interest with a performance that classical computers cannot match. Such a demonstration would involve: 1) using actual quantum hardware to run such a quantum algorithm and 2) showing that classical computers cannot perform as well.
  
  I will give an introduction on behalf of the IHPC quantum computing team on our holistic hardware-agnostic full-stack approach aiming to harness quantum computers' power to produce a practical quantum advantage in this talk. I will also introduce some of our current ongoing collaboration efforts, especially our contributions to Singapore's national efforts on quantum computing.

• Kristel Michielsen, Jülich Supercomputing Centre

• "The entanglements between high-performance and quantum computers"

• Quantum computing promises unprecedented possibilities for important computing tasks such as quantum simulations in chemistry and materials science or optimization and machine learning. With this potential, quantum computing is increasingly attracting interest from industry and scientific communities that use high performance computing (HPC) for their applications. These pilot users are primarily interested in testing whether available quantum computers today or in the foreseeable future are suitable for simulating increasingly complex systems, analyzing large data sets using machine learning methods or performing the hardest optimization task.
  
  Access to quantum computer emulators running on HPC systems and to quantum computing systems at the forefront of development is the prerequisite for testing, benchmarking, algorithm and use case design activities, and first serious applications in scientific and engineering challenges.
  
  Benchmarking quantum computers and algorithms requires emulators that can efficiently utilize the architecture of present day supercomputers. As the simulation of universal quantum computers requires a large number of matrix-vector updates, most of which are 2-component and 4-component tensor operations, the task of simulating quantum computers is an ideal candidate to profit from recent developments in the GPU industry. We present benchmarks of some of the most powerful supercomputers using the Jülich universal quantum computer simulator (JUQCS).
  
  Practical application requires the integration of quantum computers into existing HPC infrastructures in the form of quantum-classical hybrid computing models.
  
  The Jülich UNified Infrastructure for Quantum computing (JUNIQ), a manufacturer-independent quantum computing user facility established at the Jülich Supercomputing Centre (JSC) aims to address all these needs.
  
  As example, we present benchmarking results for the quantum approximate optimization algorithm (QAOA) emulated on a supercomputer and for the D-Wave quantum annealers for the tail assignment problem, a planning problem from aircraft industry.

Panel Discussion : HPC for Quantum Computing and Quantum Computing for HPC

Moderator : Nobuyasu Ito, RIKEN R-CCS

Panelists :

• Kristel Michielsen (Jülich Supercomputing Centre)
• Rodney Van Meter (Keio University)
• Ye Jun (A*STAR)
• Mitsuhisa Sato (RIKEN R-CCS)
• Seiji Yunoki (RIKEN R-CCS)