I do know of Julia-only companies, and of lots of science Julia is used for, but it’s historically being playing catch-up, and I know of no field, or sub-field (I hear e.g. particle physics could be a candidate), where Julia has taken over for most users, e.g. from Python.
That said, I’m continually amazed by the breadth (and depth, I can’t always judge that) of the Julia package ecosystem. I doubt any language comes close (Python and R would be on the short-list, I think neither has the same breath).
I know SciML is one of the many state-of-the-art Julia packages/ecosystems, but it’s a tool (not for one specific field, could have taken over in one (sub)field, but not overall), and while differential equations are very important for science, I think people haven’t yet migrated to it.
Basically where are the success stories to point to, or even likely to happen soon (judged by Julia adoption in University courses).
One example of a very specific package (renamed from KM3NeT.jl): GitHub - tamasgal/NeRCA.jl
NeRCA (Neutrino Research with Cosmics in the Abyss) is a Julia package to access and analyse KM3NeT related data. It can read the official KM3NeT ROOT and formats, calibration information (DETX files) and also live data from running detectors.
The Cubic Kilometre Neutrino Telescope, or KM3NeT, is a future European research infrastructure that will be located at the bottom of the Mediterranean Sea. It will host the next-generation neutrino telescope in the form of a water Cherenkov detector with an instrumented volume of several cubic kilometres distributed over three locations in the Mediterranean