  Point defects in two-dimensional materials are of key interest for quantum
information science. However, the space of possible defects is immense, making
the identification of high-performance quantum defects extremely challenging.
Here, we perform high-throughput (HT) first-principles computational screening
to search for promising quantum defects within WS$_2$, which present localized
levels in the band gap that can lead to bright optical transitions in the
visible or telecom regime. Our computed database spans more than 700 charged
defects formed through substitution on the tungsten or sulfur site. We found
that sulfur substitutions enable the most promising quantum defects. We
computationally identify the neutral cobalt substitution to sulfur (Co$_{\rm
S}^{0}$) as very promising and fabricate it with scanning tunneling microscopy
(STM). The Co$_{\rm S}^{0}$ electronic structure measured by STM agrees with
first principles and showcases an attractive new quantum defect. Our work shows
how HT computational screening and novel defect synthesis routes can be
combined to design new quantum defects.
