How Prof. Katja Nowack Shaped My Quantum Trajectory

When we reconnected earlier this year Prof. Katja Nowack (Physics department of Cornell) was surprised to hear that I consider her my scientific mentor. After all, she was ‘only’ a graduate student herself when she supervised my undergraduate research project. Yet, Prof. Nowack played a very important role in my early scientific career. Looking back, I realize that if it weren't for her, I may not have pursued an academic career in quantum information science. Her encouragement and guidance inspired me to explore this fascinating field more deeply, and her support gave me the confidence to pursue a graduate degree and eventually become a physics professor.

It was around 2006 and I distinctly remember the roaring press releases. ‘TU Delft Physicists make electron spin and turn’. The group of Prof. Lieven Vandersypen had managed to trap individual electrons in a gate defined semiconductor quantum dot and demonstrated single spin rotations. The experiment had connections to MRI, but with single spins, and could become a building block for future quantum computers. I got accepted to do a BSc thesis research project with the group and was tasked to improve electron spin on the setup that Katja was working on at the time.

My goal was to simulate so called composite pulse sequences that were invented for MRi applications to test if they could improve fidelity of the electron spin control pulses. I was assigned a desk and computer in the common coffee/student area and in the first weeks I remember being very overwhelmed by the realization that I did not know nearly enough about any of these topics. Katja spent countless hours with me to look at my Matlab code, teach me rotations on the Bloch sphere (‘doing the spin dance’) and later to proof-read my thesis. When the physics started to click and my simulations started to produce results, I remember Katja’s enthusiasm every time I would show her a new plot. Until then, I had never seriously considered a career in academia, but my experience in the group changed that perspective.

I stayed in Delft to enter a master program and would occasionally run into Katja. We would catch up and towards the end of the conversation she would always ask me when I would rejoin the quantum group. Back then, I briefly considered delving into solar cell research, but with Katja's and Prof. Miriam Blaauboer's unwavering support and encouragement (the latter being a committee member for my undergraduate thesis), I found my true calling in 'Team Diamond'. That's where I did my master thesis and Ph.D. thesis work, focusing on quantum measurement and feedback using NV centers.

In the acknowledgments of her PhD thesis, Katja wrote: “Good luck with the rest of your PhD. Machiel, I am sure the composite pulses will be used sooner or later.” Her words proved prophetic, as I ended up using composite pulses in my PhD research, despite the fact that they were not utilized in the experiment during my undergraduate project.

Today, I am grateful for the impact that Prof. Katja Nowack had on my life and career. I recently had the pleasure of hosting her at the University of Rochester where she gave a talk and toured my lab (picture). I still admire her passion, enthusiasm, and care as a scientist, and I hope to pass on her legacy to my own students, inspiring them to pursue their passions and reach their full potential.

Machiel Blok 

Assistant Professor of Physics

University of Rochester