Simulating the weak death of the neutron in a femtoscale universe with near-Exascale computing

TL;DR

This paper advances the numerical simulation of neutron properties using Lattice QCD on near-Exascale supercomputers, improving efficiency and enabling precise calculations of neutron lifetime.

Contribution

It introduces an improved algorithm and resource management techniques for large-scale QCD simulations on supercomputers, enhancing computational efficiency and accuracy.

Findings

Achieved 20% GPU performance with autotuning

Developed optimal application mapping for CPU-GPU interleaving

Enabled precise neutron lifetime calculations via Lattice QCD

Abstract

The fundamental particle theory called Quantum Chromodynamics (QCD) dictates everything about protons and neutrons, from their intrinsic properties to interactions that bind them into atomic nuclei. Quantities that cannot be fully resolved through experiment, such as the neutron lifetime (whose precise value is important for the existence of light-atomic elements that make the sun shine and life possible), may be understood through numerical solutions to QCD. We directly solve QCD using Lattice Gauge Theory and calculate nuclear observables such as neutron lifetime. We have developed an improved algorithm that exponentially decreases the time-to solution and applied it on the new CORAL supercomputers, Sierra and Summit. We use run-time autotuning to distribute GPU resources, achieving 20% performance at low node count. We also developed optimal application mapping through a job manager, which allows CPU and GPU jobs to be interleaved, yielding 15% of peak performance when deployed across large fractions of CORAL.