Group III Defects in Diamond for Quantum Information Applications

Point defects in wide bandgap semiconductors have emerged as leading spin-photon interfaces for applications in quantum information science. In particular, several types of color centers in diamond have been characterised as promising candidates for spin-photon interfaces. However, no color center has yet demonstrated the required spin initialisation, spin coherence and optical stability required for easy integration into quantum devices. Here, we discuss theoretical and experimental results for a new class of color centers, the group III vacancy complexes in diamond, and in particular the negatively-charged gallium vacancy center. These group III color centers are predicted to be stable in an inversion-symmetric configuration, which makes their optical transition resilient to charge noise, and therefore well-suited to integration in nanostructures. Furthermore, they are thermodynamically stable in a spin-1 charge state, which gives them desirable level structures and spin coherence properties for quantum information applications. Based on these results, we comment on the suitability of these new color centers as spin-photon interfaces.