  Diamond photonics is an ever growing field of research driven by the
prospects of harnessing diamond and its colour centres as suitable hardware for
solid-state quantum applications. The last two decades have seen the field been
shaped by the nitrogen-vacancy (NV) centre both with breakthrough fundamental
physics demonstrations and practical realizations. Recently however, an entire
suite of other diamond defects has emerged. They are M V colour centres, where
M indicates one of the elements in the IV column of the periodic table Si, Ge,
Sn and Pb, and V indicates lattice vacancies, i.e. missing next-neighbour
carbon atoms. These centres exhibit a much stronger emission into the zero
phonon line then the NV centre, they display inversion symmetry, and can be
engineered using ion implantation all attractive features for scalable quantum
photonic architectures based on solid-state, single-photon sources. In this
perspective, we highlight the leading techniques for engineering and
characterizing these diamond defects, discuss the current state-of-the-art of
group IV-based devices and provide an outlook of the future directions the
field is taking towards the realisation of solid-state quantum photonics with
diamond.
