Scalable parallel simulation of quantum circuits on CPU and GPU systems

Abstract: Quantum computing enables parallelism through superposition and entanglement and offers advantages over classical computing architectures. However, due to the limitations of current quantum hardware in the noisy intermediate-scale quantum (NISQ) era, classical simulation remains a critical tool for developing quantum algorithms. In this research, we present a comprehensive parallelization solution for the Q$^2$Chemistry software package, delivering significant performance improvements for the full-amplitude simulator on both CPU and GPU platforms. By incorporating batch-buffered overlap processing, dependency-aware gate contraction and staggered multi-gate parallelism, our optimizations significantly enhance the simulation speed compared to unoptimized baselines, demonstrating the effectiveness of hybrid-level parallelism in HPC systems. Benchmark results show that Q$^2$Chemistry consistently outperforms current state-of-the-art open-source simulators across various circuit types. These benchmarks highlight the capability of Q$^2$Chemistry to effectively handle large-scale quantum simulations with high efficiency and high portability.