Otto Hahn Medal for Joannis Koepsell

For his outstanding dissertation, Joannis Koepsell, former doctoral student of Immanuel Bloch, receives the Otto Hahn Medal, the Max Planck Society's doctoral award for excellent junior scientists.

In 2018, Joannis Koepsell and his colleagues in Christian Groß's research group at MPQ experienced a magnetic moment: The physicists from Garching succeeded for the first time in photographically imaging the magnetic environment of mobile perturbations in a crystal lattice, so-called magnetic polarons, using a quantum simulator. With their results, they provided the first experimental high-resolution images of the dressing cloud of such quasiparticles. These measurements offer a novel approach to the question of which role magnetic polarons play in the formation of exotic phenomena – such as high-temperature superconductivity.

Using a quantum gas microscope, Joannis Koepsell and his colleagues produced tens of thousands of images of two-dimensional doped antiferromagnetic systems in a lithium-based quantum simulator. A particular challenge was the development of the simultaneous spin and charge resolution of the setup. This full resolution enabled the team to directly photograph magnetic polarons for the first time (by measuring correlations between spins and charges). For this outstanding achievement in the context of his doctoral thesis titled "Quantum simulation of doped two-dimensional Mott insulators", Joannis Koepsell has now been awarded the Otto Hahn Medal by the Max Planck Society.

"This prestigious award marks a special moment in my life. To advance science, you have to keep trying to push the boundaries of what is possible. I am delighted that our progress is seen as a significant step ahead in quantum technology. It fascinates me to observe how a mysterious macroscopic phenomenon emerges from the simplest microscopic components. The measurements in this work were a dream come true for me."

After his doctorate and a brief term as a postdoctoral researcher at MPQ, Joannis Koepsell took his knowledge to the semiconductor industry. Today, as Project Manager Research & Development at the technology group ZEISS Semiconductor Manufacturing, he is responsible for developing repair solutions for photomasks used in the manufacture of high-end computers and smartphone chips.

Since 1978, the Max Planck Society has awarded the Otto Hahn Medal to up to 30 young scientists each year for outstanding scientific achievements in connection with their dissertation. The award is usually presented during the annual meeting of the Max Planck Society the following year.