Identification and tunable optical coherent control of transition-metal spins in silicon carbide

Color centers in wide-bandgap semiconductors are attractive systems for quantum technologies since they can combine long-coherent electronic spin and bright optical properties. Several suitable centers have been identified, most famously the nitrogen-vacancy defect in diamond. However, integration in communication technology is hindered by the fact that their optical transitions lie outside telecom wavelength bands. Several transition-metal impurities in silicon carbide do emit at and near telecom wavelengths, but knowledge about their spin and optical properties is incomplete. We present all-optical identification and coherent control of molybdenum-impurity spins in silicon carbide with transitions at near-infrared wavelengths. Our results identify spin S = 1/2 for both the electronic ground and excited state, with highly anisotropic spin properties that we apply for implementing optical control of ground-state spin coherence. Our results show optical lifetimes of ~60 ns and inhomogeneous spin dephasing times of ~0.3 μs, establishing relevance for quantum spin-photon interfacing. A study of defects in silicon carbide could enable the integration of quantum and standard telecommunications technologies. Defects in semiconductors are attractive systems for quantum technologies as quantum states can be prepared that have both long lifetimes and bright optical properties. Their optical transitions often lie outside of telecommunication wavelengths, however, which limit their potential use in and integration with standard communication technology. Tom Bosma from the University of Groningen and an international team of collaborators now show that they can optically control molybdenum defects in silicon carbide, which have transitions at the technologically important near-infrared wavelengths, showing that this is a promising platform for interfacing quantum and telecommunications technologies.