Quantum++

This is a modern C++ general purpose quantum computing library, composed solely of template header files. Written in standard C++17, it has very low external dependencies, primarily using the Eigen linear algebra library and optionally multiprocessing. It is not restricted to qubit systems or specific tasks, being capable of simulating arbitrary quantum processes. The main design factors were ease of use, high portability, and high performance. Simulation capabilities are limited only by available physical memory. A Python 3 wrapper, pyqpp, is also available.