Björn Sbierski | Meet the MCQSTians: in this series, we regularly feature members of the MCQST community.

"The broader research environment in Munich is outstanding"

Björn Sbierski is an MCQST START Fellow who joined the group of Jan von Delft at LMU in the summer of 2021. We invited him to share what he enjoys most about his career, why he returned to Munich, and his advice for early career scientists.

Can you briefly explain your research within the START Fellowship?

One goal of my group is to find novel ways to theoretically simulate models of frustrated quantum spins, especially at finite temperatures and in two and three spatial dimensions. These models are realized in a wide variety of experimental systems, from solid state magnets that look like little rocks to cold atomic quantum simulators housed in vacuum chambers with lots of instrumentation around, like at MPQ. We are exploring the potential of various functional renormalization group ideas that reformulate the spin-problem as a set of millions of coupled differential equations that need to be solved on supercomputers. This is all but straightforward, and it is crucial to develop an understanding for the approximations involved to capture the prevailing physics in the experiment.

What does your day-to-day work look like?

Although working from home seems tempting and possible as a theorist, I enjoy coming to my office at LMU. After 14 months living and working in a tiny apartment in San Francisco due to the pandemic, it is great to go back to a regular desk.

I like to start early in the morning, when the building is still quiet. I make a cup of tea and read the arxiv eMail alert, which summarizes the abstracts of all the new work in my field that has been uploaded to the online repository in the last 24 hours. This is a habit I have cultivated over the years; it keeps me up to date and continuously creates new research ideas.

Then I turn to my research work, and for the current term, I also dedicate a good amount of my time to my field theory lecture. If possible, I try to talk to my students in person at least once a week, or otherwise we collaborate virtually. I try to join the larger group for lunch as often as I can. There are still a number of high-profile virtual seminar series up and running, and I try to attend the most relevant talks or at least watch the recording if it would be too late in the evening. I often conclude my day with a video call to California, when my collaborators from my time at Berkeley have just finished breakfast.

Did you always want to be a quantum scientist when you were younger?

Actually, no. After high school, I told myself that I wanted to be an engineer, so I went and obtained a diploma in what was called "Microsystems engineering". However, after just one year in, I realized that the courses I enjoyed most were math and physics lectures, and that I was drawn to understanding nature in depth. So I tried my best to study physics on the side. For the last two years of my studies I came to TUM, where I cultivated an interest in theory. This eagerness and curiosity for how nature works still drives me out of bed every morning.

If you weren't a scientist, what do you think you would be doing now?

Besides curiosity, an important trait for a physicist is creativity. I like to create and solve problems, so this is why engineering seemed promising as a possible career option. I also take a lot of pleasure in interaction with students; sharing excitement and teaching come naturally to me. So, maybe a career as a high-school teacher would have been a possibility.

What drew you to Munich (and MCQST)?

As I said above, I am not a stranger to Munich. I studied at TUM for two years and this is where I met some of those professors that deeply inspired me and drew my attention to a career in theoretical physics. During the diploma thesis I worked with Jan von Delft at LMU, and we stayed in contact for many years until I heard of the START Fellowship and chose him to host my application. I knew that his group would be the perfect match for me and my research agenda.

The most attractive aspects of the START Fellowship are its independence and the opportunity to hire and supervise students. This is what I wanted all along: to share my ideas with young and eager colleagues and to try out as many of my ideas as possible. In addition, the broader research environment in Munich is outstanding, and I have just started to reach out and explore by visiting MPQ, and I have another lab visit scheduled at TUM in Garching next week.

What was your most memorable moment or proudest achievement in your research at MCQST thus far?

As I started only recently in fall, many of the new projects are still on the way. However, in December, when the compute cluster finished calculations using our newly developed simulation method for spin systems, I was very pleased to see how well the data reproduced existing benchmark results. This was when I realized that my hopes I had put into this new method might become true, and recently, more and more colleagues seem to be getting excited about it as well.

Besides my own research, I am always excited when the students I supervise give their weekly research updates in the meeting within the larger group. It feels good to see that those fragile and vague research ideas that you handed over to them are prospering, being pushed on by the student's curiosity and ingenuity, and how less and less oversight is required with each new equation and figure added to a thesis work.

"The most attractive aspects of the START Fellowship are its independence and the opportunity to hire and supervise students."

Outside of science, what do you enjoy doing most?

With an office job all revolving around equations, computer codes, and thinking, I enjoy going outdoors to balance my life. I love hiking and mountaineering, biking, running, skiing -- whatever you can do outside. Often enough, good ideas or solutions for pressing physics problems come naturally once I leave the office and get to spin my legs on my bike.

What advice would you give to someone at the beginning of their physics career?

Pick a PhD advisor who you personally like and get along with. It must feel comfortable sitting together and talking science. And it should be fun -- otherwise it is not right and you are probably wasting your time.

Start pursuing your own research ideas early. Don't wait for your advisor to feed you ideas.

And take your questions seriously: If there is a step in your calculation that you don't quite understand, and you wonder about it but just move on, it is most certainly coming back to bite you.

Reach out to other researchers you find inspiring early, even if they are kind of famous. You will find out that most of them like to share their knowledge and enthusiasm.

What kind of support do you think it’s important for early career scientists to have?

I think it is crucial to have some independence in the choice of your projects, and some experienced scientists to talk to and bounce off ideas. On the other hand, I found it important to advise students early on to grow into the mentor role.

Find out more about our START Fellowship and Björn's research.