Alkali-metal vacancy defects in silicon for telecom emitters

Silicon is a technologically mature material which makes it an excellent host for quantum defects with integrated quantum technology applications. Several point defects were theoretically investigated in this platform, while single photon emitters and spin-photon interface defects were demonstrated experimentally. We apply first-principles calculations on alkali-metal-saturated vacancy complexes in search of a combination of telecom-wavelength emission with ground-state spin properties for quantum repeater and distributed sensing applications. Based on the localization effect of the defect orbitals, we propose the positively charged sodium variant of the experimentally known Q-center in silicon as a promising candidate.