Charting a Path in a Shifting Technical and Geopolitical Landscape: Post-Exascale Computing for the National Nuclear Security Administration

In 2022, the United States installed its first exascale computing system for the Department of Energy (DOE) Office of Science, with an National Nuclear Security Administration (NNSA) system scheduled for 2023. The DOE Exascale Computing Project (ECP)2 has developed new applications capabilities, parallelization approaches, and software tools, while co-developing the computing systems in collaboration with vendor partners. The NNSA is positioned to take full advantage of exascale computing, but demand for more computing will continue to grow beyond exascale, driven by both familiar applications and new mission drivers and new computational approaches that will use high-end computing. Visionary leaders and creativity will be needed to move existing codes to next-generation platforms, to reconsider the use of advanced computing for current and emerging mission problems, and to envision new types of computing systems, algorithmic techniques implemented in software, partnerships, and models of system acquisition. This report reviews the future of computing beyond exascale computing to meet national security needs at the National Nuclear Security Administration, including computing needs over the next 20 years that exascale computing will not support; future computing technologies for meeting those needs including quantum computing and other novel hardware, computer architecture, and software; and the likely trajectory of promising hardware and software technologies and obstacles to their development and their deployment by NNSA.