  Real-world quantum applications, eg. on-chip quantum networks and quantum
cryptography, necessitate large scale integrated single-photon sources with
nanoscale footprint for modern information technology. While on-demand and high
fidelity implantation of atomic scale single-photon sources in conventional 3D
materials suffer from uncertainties due to the crystals dimensionality, layered
2D materials can host point-like centers with inherent confinement to a sub-nm
plane. However, previous attempts to truly deterministically control spatial
position and spectral homogeneity while maintaining the 2D character have not
been realized. Here, we demonstrate the on-demand creation and precise
positioning of single-photon sources in atomically thin MoS2 with very narrow
ensemble broadening and near-unity fabrication yield. Focused ion beam
irradiation creates 100s to 1000s of mono-typical atomistic defects with
anti-bunched emission lines with sub-10 nm lateral and 0.7 nm axial positioning
accuracy. Our results firmly establish 2D materials as a scalable platform for
single-photon emitters with unprecedented control of position as well as
photophysical properties owing to the all-interfacial nature.
