Pau Farrera | Meet the MCQSTians: In this series, we regularly feature members of the MCQST community and offer insights into their research and career.

"While performing experiments with individual atoms and photons I feel we are exploring nature on a deep level."

Pau Farrera's research interests sparked during his bachelor studies at the University of Barcelona, where he did two research internships (one theoretical and another one experimental) related to quantum entanglement and Bell’s theorem. Later, he further explored these concepts pursuing a PhD at the Institute of Photonic Sciences (ICFO in Barcelona) using laser-cooled atoms to generate quantum states of light and matter in the context of quantum communication. In general, Pau's main research interest focuses on gaining control over the quantum state of individual atoms and photons and looking towards applications in quantum cryptography, metrology and computation.

Can you briefly explain your research project? What are your main research goals?

In general terms, my research within the START Fellowship will push forward the control over the quantum state of individual photons and atoms. In particular, we will use an experimental platform where single atoms are strongly coupled to two crossed optical resonators, which consist of two pairs of mirrors located at the end facet of optical fibres. Using fibre resonators has the advantage that the four mirrors can be very close together (with cavity length around 100μm), providing a strong coupling between the atom and the photonic cavity modes. One goal will be to generate entangled states involving the atom and photons in each cavity mode. Another goal will be to use the atom as a mediator for the interaction between qubits encoded in photons in each cavity mode. We will look into the application of these schemes in the field of quantum communication, with the main goal of distributing atomic entanglement over large distances. Whenever trying to gain control and manipulation precision over a physical system new questions arise and new possibilities appear, and this is the process that I am mostly looking for.

Did you always want to be a quantum scientist when you were younger? And if you weren't a scientist, what do you think you would be doing now?

As a kid, I mostly wanted to be an inventor and enjoyed thinking creatively about simple devices that would make my life easier. Later reading books about astronomy and the universe sparked my curiosity and motivated me to study physics. During my bachelor studies, I enjoyed learning about the concepts of quantum superposition and entanglement and the new technologies that such concepts may enable. That was the time when I realized that being a scientist in quantum physics would satisfy both my interests for scientific curiosity and technology creativity. I never thought much about what would happen if I weren’t a scientist, but I would probably have an engineering job or be a physics high school teacher.

What drew you to Munich (and MCQST)?

During my PhD studies, I had the opportunity to go on a short internship (awarded by the Prince of Asturias Foundation and MPG) at the Max Planck Institute of Quantum Optics (MPQ). It was supervised by Prof. Gerhard Rempe and Dr. Stephan Ritter, and both the research topic and the scientific discussions I had with the group were very stimulating. In addition, I could see very closely the great infrastructure and support provided to the scientists in the institute. During this time, I also had the opportunity to attend an event organized by the Munich Quantum Center, where I could learn about the broad and outstanding quantum science environment in Munich. After finishing my PhD I had another opportunity (this time awarded by the Cellex foundation) to continue my research at MPQ. Considering all these aspects, I did not think twice about it and decided to continue my research in Munich and MPQ. In addition to the outstanding scientific landscape in Munich, I also like its rich cultural environment.

"Follow a research path that you feel passionate and curious about. Passion and curiosity for a topic are what can bring someone far despite any challenge found in their path."

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

My main advice is probably an obvious one, but above all, I would follow a research path that you feel passionate and curious about. Passion and curiosity for a topic are what can bring someone far despite any challenge found in their path.

I would choose an advisor who you personally like and get along with. Stimulating discussions about science with your advisor is very important to get good and creative ideas at an early stage.

Finally, I would advise you to reach out without hesitation to scientists that you admire. They will most likely be happy to answer your questions about their research, and with every interaction, you will broaden your knowledge.

What is it about your field of research that gets you most excited?

What excites me the most about our research field is that besides the very interesting quantum physics concepts that we explore, it also has implications in new technologies. While performing experiments with individual atoms and photons I feel we are exploring nature at a quite deep level. The combination of this exploration with the development of new technologies is something that makes me feel excited about my work. In addition, I also like the fact that our experiments do not require big facilities and a large number of people to be operated. This means that we can be quite dynamic and flexible in implementing the ideas that we have with our experimental platform.

Outside of science, what do you enjoy doing most?

In my free time I enjoy practicing most outdoor activities and sports, currently running, gardening, and hiking are my favorite ones. Another interest I have is music, both going to concerts and playing piano. I’m currently not performing in any music band, but we had a good time assembling a Christmas choir together with some of my colleagues. We rehearsed for few weeks and performed during the Christmas lunch event in our institute.

Find out more aboout the START Fellowship and Pau's research.