Qrack

Using the C++11 standard, at base, Qrack has an external-dependency-free CPU simulator "engine," as well as a GPU simulator engine that depends only on OpenCL. The QUnit layer provides novel, fundamental optimizations in the simulation algorithm, based on "Schmidt decomposition," transformation of basis, 2 qubit controlled gate buffer caching, the physical nonobservability of arbitrary global phase factors on a state vector, and many other "synergistic" and incidental points of optimization between these approaches and in addition to them. QUnit can be placed "on top" of either CPU, GPU, or hybrid engine types, and an additional QPager layer can sit between these, or in place of QUnit. Optimizations and hardware support are highly configurable, particularly at build time.