Hybrid quantum-classical algorithms in the noisy intermediate-scale quantum era and beyond

The coming era of quantum computing promises to revolutionize computation, but, given the efficiency of many classical routines as well as quantum hardware limitations, calls to quantum devices are and will continue to be used as subroutines in larger, hybrid quantum-classical algorithms. This Perspective explores the essential differences between pure and hybrid quantum algorithms, discusses some examples, and frames the future of hybrid quantum-classical algorithms in its natural context of classical heterotic computing.