The interview process consisted out of 3 steps:
1. interview with a HR person, with general talk about the company
2. programming test
3. technical interview with people from the tech team
The procedure was fair overall. The programming test was neither too complicated, nor too easy; with a task that cannot be solved just by googling/chatgpting, and really requires some background knowledge of tensor networks. The subsequent technical interview was similar to a university oral exam, with deep domain-specific questions, as well as questions about my previous work. I believe the point was to separate people who have worked as developers of these methods, as opposed to those that just casually used iTensor or something like that.
My only critique is that the interview process was not laid out very transparently. As an interviewee, It would have been nice to know that these 3 steps are coming. The programming test took a good part of my weekend, but the subsequent technical interview made zero reference to it (at least a "thank you for your time" would have been nice!), so I don't even know how it factored into the decision process. I also didn't expect step 3 to be that exam-like because I thought that the technical assessment was done in step 2. All of this left me quite confused at the end, and not with a too good of an impression of the company. However, I think all of this can be partially explained by the fact that it's still a growing startup and things are a bit chaotic at times.