  We present the first open release of the DCA++ project, a high-performance
research software framework to solve quantum many-body problems with cutting
edge quantum cluster algorithms. DCA++ implements the dynamical cluster
approximation (DCA) and its DCA$^+$ extension with a continuous self-energy.
The algorithms capture nonlocal correlations in strongly correlated electron
systems, thereby giving insight into high-$T_c$ superconductivity. The code's
scalability allows efficient usage of systems at all scales, from workstations
to leadership computers. With regard to the increasing heterogeneity of modern
computing machines, DCA++ provides portable performance on conventional and
emerging new architectures, such as hybrid CPU-GPU, sustaining multiple
petaflops on ORNL's Titan and CSCS' Piz Daint supercomputers. Moreover, we show
how sustainable and scalable development of the code base has been achieved by
adopting standard techniques of the software industry. These include employing
a distributed version control system, applying test-driven development and
following continuous integration.
