Inspired by his grandfather, Dr Klaus Jöns of Paderborn University became a researcher and is now aiding efforts to develop photonic quantum technologies.
After obtaining his doctoral degree in physics from the University of Stuttgart in 2013, Dr Klaus Jöns took up a postdoctoral position at the quantum transport group (now QuTech) at the Kavli Institute of Nanoscience Delft in the Netherlands.
In 2015 he received a Maria Skłodowska-Curie postdoctoral individual fellowship to move to KTH Stockholm, Sweden. Since then he has received several national and international fellowships, prizes and grants. He was also the youngest coordinator of a European Quantum Flagship project called S2Quip.
In September this year, he started as a full professor in the physics department of Paderborn University in Germany as part of the newly formed Photonic Quantum Systems Institute.
‘To make a quantum internet reality, we will need the best possible quantum light source’
– DR KLAUS JÖNS
What inspired you to become a researcher?
My grandfather. He was a professor in German language and literature, as well as doctor in philosophy and history. When I was eight years old and was asked what I want to become, I always said: “What my grandfather is, but in mathematics.” At that time, I did not know about physics in school.
My grandfather was a remarkable person. I admired him, his wisdom and his sharp mind. I still remember when we had our frequent dinner discussions and an unanswerable question came up.
He would excuse himself and stand up, walking into his library at home with all the old books and the scent of pipe tobacco and his massive wooden desk with his typewriter. He would come down with a lexicon answering the open question. He was our Google search engine at the times without internet.
Can you tell us about the research you’re currently working on?
I work on solid-state quantum light sources and their applications. I have to admit that I was very lucky to have a great high school education. I had a fantastic physics teacher who said ‘What is…?’ are the hardest questions to answer because a lot of things have different interpretations, which became more clear when we starting talking about ‘what is light’.
Since then I was fascinated by light and focused my studies at university on semiconductor, quantum optics and photonics. I started my PhD on semiconductor nanostructures as quantum light sources. Back in 2009, I thought I would not find a professor position in this field.
However, thanks to people like my supervisor and others who continued to do basic research on this topic, a lot of breakthroughs happened between 2014 and 2016. Nowadays, solid-state quantum light sources are one of the major building blocks for photonic quantum technologies.
In your opinion, why is your research important?
Photons, which are particles of light, are the only reliable information carrier which can transmit quantum information over long distances. This makes photons a unique type of quantum information carrier (qubit) and they are often referred to as flying qubits.
Independently, whichever material platform will finally win the race to build a fully functional quantum computer, photons will be needed to link those devices. And linking computers is what made them so powerful in our daily lives. Imagine a world without the internet. Then you would need a big library like my grandfather once had. To make a quantum internet reality, we will need the best possible quantum light source.
What commercial applications do you foresee for your research?
Apart from the dream to have a quantum internet with secure quantum communication for everyone, our sources also impact other photonic quantum technologies.
First of all, companies like PsiQuantum are building a quantum computer based on photons, which allows for easier scalability than other platforms. However, this concept has other major challenges.
Secondly, I envision quantum light sources to increase sensitivity on sensing applications, such as quantum lidar, super-resolution and entanglement-enhanced microscopy for biomedical applications.
What are some of the biggest challenges you face as a researcher in your field?
Losses! Transmission losses of photons due to absorption or loss of coherence of the precious quantum properties we want to use as resources. Any unwanted interaction of our quantum system with the environment leads to a loss of quantum information.
Are there any common misconceptions about this area of research?
That quantum technology for everyday life is around the corner. Sure, it is great being part of this hype, but we still need to solve a lot of fundamental and technological challenges.
Physicists alone cannot bring quantum technologies to market, we need to work together with engineers, computer scientists and so on. We see this change slowly happening and I am happy being part of it with the multidisciplinary Photonic Quantum Systems Institute.
What are some of the areas of research you’d like to see tackled in the years ahead?
Environmental economics, climate change and inequality. I doubt that we still need quantum technologies in 100 years if we don’t tackle these issues first.
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