“Ursi, explain that to us”

© Photo | KD Busch

How does one become professor of quantum physics at the best university in Switzerland at the age of 33? For Ursula Keller it was grit, talent - and a bit of luck.

Professor Keller, your chances of having a scientific career were not very good at first. So what brought you to physics ?

I come from a working­class family and it was clear that I would take on an apprenticeship af­ter secondary school. As part of the vocational guidance process, I had to take an IQ test. And when the guidance counselor was evaluating the test, she suddenly became very quiet. I guess I was good. She then asked me if I wouldn’t rath­er continue on in my schooling and suggested that to my father. It’s thanks to her advice that I graduated from college at all. Even if my teacher was against it.

There is more
The Laser Institute of America awared Prof. Ursula Keller the Arthur L. Schawlow Award 2013.

The Laser Institute of America awared Prof. Ursula Keller the Arthur L. Schawlow Award 2013.


The Swiss physicist developed a technology for the simple generation of extremely short laser pulses, making ultrafast lasers available for industry. Her development, the Semiconductor Saturable Absorber Mirror (SESAM), opens up broad technological applications in measurement technology, medicine and materials processing.


Prof. Keller received the 2004 Berthold Leibinger Innovationspreis and the 2005 Philip Morris
Forschungspreis 2005 for SESAM, among other things. For outstanding contributions to research in laser science the Laser Insitute of America awarded Ursula Keller the highly reputable Arthur L. Schawlow Award.


In 1994, she and her husband, Dr. Kurt Weingarten, founded the company Time-Bandwidth Products to market her patented and trademarked SESAMs.

The teacher was against it?

Well, you should know that my talent is very one­sided. In language studies I was very bad at school, but then I was very good at math. When the teacher had no more answers, my classmates always said, “Ursi, explain that to us.” The teacher couldn’t deal with the situation and didn’t really support me.

Did that influence your attitude toward the educational system?

I am a very strong advocate for well­equipped public schools and a completely open path­ way to the top. That opens the door for late bloomers and kids with a one­sided talent. But I have a real problem with the private schools springing up here. Only rich people can afford them and it is not a law of nature that they will automatically produce the most intelligent offspring.

Speaking of children, you were back working full-time at ETH only a few weeks after the birth of each of your two sons. What kind of lifestyle does that represent?

At the time I was often asked why I had children at all. Would anyone ever ask this question to a father with a career? It can’t be that you slave away and struggle for years only to suddenly be sent home. Don’t misunderstand me: We have children because we want children. But it’s a matter of quality and not only quantity when it comes to spending time with family. And also when they were babies, both of them had the best care you could find.

But one has to be able to afford that care…

That is less of a financial problem than a structural one. The costs of preschool here in Switzerland depend on the income – therefore anyone can afford it. But there are not enough spots available and not enough all­day schools.And if children cannot be cared for during the afternoon, then that is simply a problem for working women.

How do you manage your various roles as mother, professor and entrepreneur?

In reality, my husband is the entrepreneur of the family. I only sit on the supervisory board. My children not only have a mother but a father as well. And, of course, in my heart of hearts I am a professor, but I also have a team of 25 or 30 people behind me.

As a female physicist do you have to fight problems of acceptance among male physicists?

Ursula Keller is specialist for ultra-short pulsed lasers at ETH Zurich.

Ursula Keller is specialist for ultra-short pulsed lasers at ETH Zurich.

People joining my team don’t have any prob­lem with a female boss. And those who do, stay away. But there is something else that I had to get a handle on at first: Because I am no longer knee­deep in every experiment, people often know the details better than I do. And now and again there are Ph.D. students and espe­cially postdocs who make that known. I have discussed that among colleagues. I guess it’s not a problem typical to any gender. We all have to put up with it.

Getting back to the start of your career, were you a geek at school?

I think so. My hair was too short, my glasses too thick and I was very good in math – bet­ter than all the guys in the class. That wasn’t exactly optimal for dating.

How did you deal with that?

I began studies in physics at ETH in Zurich and had the opportunity to start something like a new life. I enjoyed the new freedom, went to every party, and up until the preliminary diploma, I wasn’t very industrious.

Nevertheless after graduation, you were accepted at Stanford as a Ph.D. candidate…

Yes, I absolutely wanted to go abroad, prefer­ably to a good university in the United States. So I really went all out for the diploma exams. Of the five American universities that I ap­plied to, all five accepted me. I decided on Stanford.

You met your husband there and had a “bi-coastal marriage.” What can we make of that?

It happened like this: my husband Kurt is an electrical engineer and had a good job on the West Coast. But my dream job was waiting for me a couple thousand miles away at Bell Labs on the East Coast. It was a tough decision but I knew that if I didn’t follow my dream for the sake of my husband that at some point I would resent him for it. So I went.

Was that due to strong resolve, seizing the opportunity or egoism?

You can call it egoism if you like. But my hus­band and I think that we share a very healthy and honest egoism, even now that we have been living together again for a long time. Our partnership is not based on self­denial and substitution. We’re together because it’s good for the individual. And besides, it was very romantic at the time to meet somewhere once a month between the East and West Coast for an extended weekend.

But then in fact you did give up your dream job at Bell. How did that happen?

Ursula Keller's developments made ultra-short pulsed lasers available for industry.

Ursula Keller’s developments made ultra-short pulsed lasers available for industry.

One day the phone rang. It was ETH and they offered me a professorship. At first I laughed and asked them if they knew how old I was. I was 33 at the time and actually didn’t want the job. But the offer kept getting better so I took the plunge.

And your husband, what did he say?

He said OK, if you have a good job and can earn enough for the both of us, then I’ll go to Switzerland and risk starting up my own laser company. At the time it was one of the first spin­offs of ETH and is now very success­ful – due to SESAM.

Have you ever regretted the change from the American economy to Swiss science?

At Bell I conducted every experiment my­self. Because of capacity issues, many ideas fell by the wayside. Here at ETH, there is a large team and I have the opportunity to put several things into motion at the same time. I very much like being a researcher in academia; there are still so many limits to be figured out.

This article was first published in spring 2007.

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