  Modeling plasma accelerators is a computationally challenging task and the
quasi-static particle-in-cell algorithm is a method of choice in a wide range
of situations. In this work, we present the first performance-portable,
quasi-static, three-dimensional particle-in-cell code HiPACE++. By decomposing
all the computation of a 3D domain in successive 2D transverse operations and
choosing appropriate memory management, HiPACE++ demonstrates
orders-of-magnitude speedups on modern scientific GPUs over CPU-only
implementations. The 2D transverse operations are performed on a single GPU,
avoiding time-consuming communications. The longitudinal parallelization is
done through temporal domain decomposition, enabling near-optimal strong
scaling from 1 to 512 GPUs. HiPACE++ is a modular, open-source code enabling
efficient modeling of plasma accelerators from laptops to state-of-the-art
supercomputers.
