QEngine: A C++ library for quantum optimal control of ultracold atoms

We present the first version of the QEngine, an open-source C++ library for performing optimal control of ultracold quantum systems. The most notable systems presented here are Bose–Einstein condensates, many-body systems described by Bose–Hubbard type models, and two interacting particles. These systems can all be realized experimentally using ultracold atoms in various trapping geometries including optical lattices and tweezers. We provide several optimal control algorithms including the group method. The QEngine library has a strong focus on accessibility and performance. We provide several examples of how to prepare simulations of the physical systems and apply optimal control.