Design for telecom-wavelength quantum emitters in silicon based on alkali-metal-saturated vacancy complexes

Defect emitters in silicon are promising contenders as building blocks of solid-state quantum repeaters and sensor networks. Here we investigate a family of possible isoelectronic emitter defect complexes from a design standpoint. We show that the identification of key physical effects on quantum defect state localization can guide the search for telecom wavelength emitters. We demonstrate this by performing first-principles calculations on the Q center, predicting its charged sodium variants possessing ideal emission wavelength near the lowest-loss telecom bands and ground state spin for possible spin-photon interface and nanoscale spin sensor applications yet to be explored in experiments.