  Given its unrivaled potential of integration and scalability, silicon is
likely to become a key platform for large-scale quantum technologies.
Individual electron-encoded artificial atoms either formed by impurities or
quantum dots have emerged as a promising solution for silicon-based integrated
quantum circuits. However, single qubits featuring an optical interface needed
for large-distance exchange of information have not yet been isolated in such a
prevailing semiconductor. Here we show the isolation of single optically-active
point defects in a commercial silicon-on-insulator wafer implanted with carbon
atoms. These artificial atoms exhibit a bright, linearly polarized
single-photon emission at telecom wavelengths suitable for long-distance
propagation in optical fibers. Our results demonstrate that despite its small
bandgap (~ 1.1 eV) a priori unfavorable towards such observation, silicon can
accommodate point defects optically isolable at single scale, like in
wide-bandgap semiconductors. This work opens numerous perspectives for
silicon-based quantum technologies, from integrated quantum photonics to
quantum communications and metrology.
