Interview with Jens Bardarson

Hello Jens, tell us a little bit about you and your educational background?

I grew up in a small town in the south of Iceland and did my undergraduate studies in physics at the University of Iceland. My PhD was with Carlo Beenakker at the Lorentz institute at the University of Leiden. Sadly, when I came to Leiden the physicists had left the Kamerlingh Onnes laboratory where Lorentz used to roam and superconductivity was discovered. After my PhD, I did a short postdoc at Cornell and a longer one at UC Berkeley before becoming a group leader at the Max Planck Institute for Complex Systems in Dresden. From there I joined KTH a few years back.

Taking up a new position is a challenge on its own. How has your time as a professor been so far, any significant changes compared to your previous position as an associate professor?

It’s only been a couple of weeks, and so far so good. To be honest not much has changed in the daily work as from the very beginning my division gave me full academic freedom and support to run my own group, which I have done since I came to KTH. This was really an essential aspect when deciding to come to KTH.

What has been the biggest challenge?

So far there have been no additional challenges that weren’t there already. The biggest challenge is always time. I have come to terms with it long time ago that there are more things I would like to do than I have time for.

Tell us about your research, what makes it important?

My research is about understanding the fundamental quantum nature of matter, resulting from elemental quantum phenomena such as quantum interference and entanglement. A big driver is curiosity and the interaction between theory and experiment is important and therefore we try to understand how to observe interesting phenomena in reality. Basic science provides the foundation on which engineering applications are built and there is no accident that all the strongest technical universities in the world have strong basic science departments. I believe quantum physics will become more and more central, with a rapidly emerging quantum technology sector requiring a solid education of “quantum engineers.”

What are the biggest challenges your research combats?

The biggest challenge is the incredibly large amount of information that can be stored in a quantum state. This is of course the reason that quantum computers can massively outperform classical computers, at least in theory. But it also means that if we want to simulate for example the quantum dynamics of many interacting particles, it is extremely hard to do on a classical computer. Just as an example, if I were to do this exactly keeping track of all information, the best computers today can only do about 20 particles. The major challenge is then how to understand many-body quantum matter?

Does your work have practical applications, if so, what would these be?

My work is very much focused on the fundamental physics of quantum matter. Therefore, it is not always directly obvious what the practical applications will be. I have worked extensively on understanding the physics of topological insulator nanowires covered with superconductors which result in the emergence of so called Majorana fermions. These Majorana fermions, with some extensions, could be used to topological quantum computing via braiding. That would be one example.

Has your work been affected by the pandemic, and if yes, are you looking forward to working from the office again?

It definitely has. One might think that it’s easy for theorists to sit at home with their computers, but there is a strong social aspect to science that is often underappreciated, and theoretical physics is no different. All the small spontaneous discussions on problems and ideas basically disappear when all the interactions you have with the group is through a screen. I miss the times when students and postdocs drop in the office to discuss what is on their mind, or when you bump into a colleague in the corridor and start discussing. That being said, we have made things work and we are lucky that it is at all possible to keep doing what we love doing even during a pandemic. 

Why did you choose your field of research in particular?

It’s hard with any certainty to say why we make any decision, I think. To some extend I have followed my nose and tried to understand things that I find interesting. In choosing research topics it has always been important to me that the theory I have been working on can, at least in principle, be verified by experiments.

What made you interested in your field?

The vast number of interesting phenomena that are realized in quantum matter. The fact that it combines fundamental physics with potential no-to-long-term applications. Quantum physics is also just really mind-boggling and fun. Since the behavior of quantum particles is so counter-intuitive, one needs to construct a new intuition for how things work. It’s like trying to understand how it is to live in a different world with completely different rules… except it is the world we live in. The concept of emergence is fundamental to quantum matter and it is fascinating how a collection of a large number of particles can collectively behave as new emergent particles. This means that “more is different;” knowing everything there is to know about a single particle is not sufficient to know how many particles will behave.

Is it important for you to communicate your research to the world, if yes why and how do you do that?

Absolutely. Mostly we communicate our research to other physicists, both through seminars and workshops, but also by making sure our research papers are publicly and freely available on the preprint server arXiv. I have also taken part in open science days, mainly in Germany, where we open the university to everyone and explain and discuss our research. This is always fun. I also recently wrote a popular science level article (in Swedish) on quantum measurements and thermalization in Kosmos, see www.fysikersamfundet.se/wp-content/uploads/Kosmos_2019_särtryck6.pdf.

What would be your message or advice to youngsters who are interested in perusing scientific professions?

Go for it! Don’t be afraid of asking senior people for help and advice (and if you don’t get an answer don’t take it personally). Understand that, like with any skill, practice makes perfect. There are no shortcuts. The earlier you start putting in the hours the more likely you are to succeed. But also enjoy life!