I received a phone call inviting me to an onsite interview at their Cambridge office. The interview took place two weeks later and consisted of three stages, each lasting around 45 minutes. Stage 1: 45 min HR Interview The first stage was a non-technical interview with an HR representative, focused on the company culture and understanding my background. Stage 2: 45 min Technical Interview with a Physicist In the second stage, I was interviewed by a physicist. The interview started with a brief discussion about my previous experiences, followed by a problem-solving session on a client's issue. Stage 3: 45 min Technical Interview with Another Physicist The third stage was another technical interview, focusing on different scenarios and problem-solving questions.