Frontier Research Institute for Interdisciplinary Sciences
Tohoku University

Quantum Chromodynamics (QCD) is the theory of the strong interaction in the particle physics, which explains the formation atomic nuclei from elementary particles. While QCD is well established, it has a major open question known as the “the strong Charge-Parity (CP) problem.” The theory predicts a violation of CP symmetry, but experiments show this violation is either extremely small or not present at all.

The CP symmetry violation is captured by a parameter called θ. Theory suggests θ could be around 1, but experiments show it must be less than 10⁻¹¹. This huge gap hints at unknown physics beyond the standard model of particle physics. To understand it, we need to analyze the QCD with very precise numerical simulations. However, classical computers struggle with this due to the complexity of quantum systems.

This project aims to develop a new algorithm using quantum computing to study the strong CP problem. We propose a hybrid quantum-classical approach that works on near-term quantum devices. Since the strong CP problem is based on the quantum physics, a quantum computing may reveal features that are hidden from classical computing approaches.

Our research combines quantum computing, high-energy physics, and algorithm design. It shows how quantum computers can be used to tackle deep problems in fundamental physics: problems that classical computing approaches can’t easily solve. By focusing on a long-standing mystery in QCD, this project highlights the potential of quantum technologies to open new paths in scientific discovery.