Colour centres are optically active defects in crystals that have recently been harnessed for emerging applications in quantum technologies such as single photon emission and quantum sensing. These optically active defects can occur naturally in materials, or they can be introduced during growth through doping. The random distribution of these defects in crystals is clearly not desirable for many device applications. A preferable method of producing colour centres in material is through ion implantation. Ion implantation is an enabling technology that allows for the direct creation of colour centres in a controlled manner and with a high degree of spatial precision.

In this work, an overview of the role that mega-electron volt (MeV) ion beams can play in the controlled creation of optically active defects will be discussed. Highly focused beams of light ions (protons and helium ions) are shown to generate vacancies in various materials that have desirable optical properties for quantum applications. Examples in wideband gap semiconductors such as diamond and silicon carbide (SiC), and in 2D materials such as hexagonal boron nitride (hBN) and transition metal dichalcogenides (TMDs) will be shown. The nature of these defects and applications for single photon emission and optically detected magnetic resonance (ODMR) sensing will be discussed.