Quantinuum Interview Questions
& Process

The first couple of interview rounds went by fast, but the third round was different. I had to create a detailed strategy presentation. This presentation needed to cover potential solutions for Quantinuum's actual business problems and include my 12-month work plan. Honestly, I felt weird about it, like I was doing free consulting. But I went ahead with it, and the hiring manager seemed to like it. He said I'd talk to more team members and their CHRO soon. The recruiter then quickly asked for my slide deck, without mentioning setting up any interviews. My gut told me this was a major red flag, so I turned it down since I had already done an in-depth presentation interview. After that, Quantinuum just ghosted me.

So, this whole thing with Quantinuum took about six months. It started when a recruiter from LinkedIn found me in late September. My first chat was a video call in early October. After that, crickets for three months. Then, mid-January 2026, they reached out again to schedule an on-site interview at their Broomfield, CO office. The on-site interviews are a full day thing, with multiple group sessions. A key part is giving a presentation about something I've worked on that's relevant to the role. This specific role is Principal / Lead Compiler Engineer. Back in October, they mentioned they wanted to improve their compiler's quality, admitting it was currently subpar. What was surprising was that in the later rounds, none of the interviewers seemed to have compiler expertise, and I wasn't asked any compiler-specific questions during the whole day. I even gave a presentation specifically about compilers, but received no questions about it. It felt like they weren't sure what they were looking for. Despite lacking compiler backgrounds, some interviewers had strong opinions on compiler development. The afternoon was more management/behavioral, focusing on team dynamics like handling disagreements and reaching consensus. One interviewer was taken aback when I said I'd admit if I didn't know something and would look it up, suggesting maybe they expected a 'fake it till you make it' response. Some of my presentations included complex code examples related to compiler development, but it seemed nobody grasped the code's subtleties, with one person admitting they couldn't parse it. I wasn't asked about the code, and had to walk through every line. Overall, a pretty disappointing and frankly concerning experience.

Quantinuum's interview process was pretty long. It took about a month from when I applied to get a screening interview. After that, the manager called me, and then I was invited for an on-site interview. The on-site involved a technical presentation, several panel interviews where they mainly asked about my presentation and past work, and a manager interview that was all about behavioral questions. After the on-site, it was radio silence for weeks. I waited for about four weeks and then just got an automated rejection letter, no feedback at all.

The interview process had two stages. The first stage was a technical interview, conducted online via Teams. It was an enjoyable panel interview with 3 people. There weren't any major surprises, it included a logic puzzle, a coding challenge, questions about cloud computing, and a code review. The second stage was a 30-minute call with the hiring manager for the group. I didn't pass this stage; I don't think my background was a good fit, and he might have been right.