For the technical recruiter round, it was a phone call (called me out of the blue I wasn't ever prepared) but it went suprisingly well. It was more like an informative call. For the technical round, it was an interview with the principal engineer, asked me a lot of high performance computing related questions (since that was what I was interviewing for). I should have prepared better, I tried to cover in breadth, instead I should have just focused on what I actually had experience in.