Ella Nikodem Receives Klaus Liebrecht Prize for Excellent Master’s Thesis
The Faculty of Mathematics and Natural Sciences awarded the Klaus Liebrecht Prize on May 9, 2025. The award was given to M.Sc. Ella Nikodem from the research group of Cluster Spokesperson Prof. Yoichi Ando, Department of Physics – 2nd Institute of Physics, for her master’s thesis. In her thesis in the subject of physics, titled “Tunnel Junction Device of Phase-Biased Topological Insulator Josephson Junction,” Ella Nikodem demonstrated outstanding commitment and achievements in experiments on topological superconductivity.
Foto: Thorsten Martin Prodekanin Prof. Dr. Katharina Groß, M.Sc. Ella Naomi Nikodem
About Ella’s Work
Quantum computers promise a fundamentally different approach to tackle certain computational processes — one particularly robust, though as yet unrealized, variant is the so-called topological quantum computer. Its key component, Majorana zero modes, could enable especially fault-tolerant quantum information. These states are expected to occur at the edges of topological superconductors. However, since no such superconductor has been found in nature, artificial structures must be created. One theoretically predicted approach is to induce topological superconductivity on the surface of a topological insulator by bringing it into contact with a conventional superconductor.
In her work, Ella Nikodem focused on the experimental realization of this concept. Using tunneling spectroscopy on a planar Josephson junction made from the topological insulator BiSbTeSe₂ and superconducting aluminum, she was able to investigate characteristic signatures of topological superconductivity. By measuring the differential tunneling conductance as a function of parameters such as chemical potential, phase difference, and an in-plane magnetic field, she carried out a detailed analysis of the energy states in the system. In certain parameter regimes, the results showed good agreement with the theoretically predicted 4π periodicity of Majorana excitations. Her work thus provides evidence for the presence of topological superconductivity and opens new experimental avenues for investigating this promising platform for future quantum applications.
About the Klaus Liebrecht Prize
The Klaus Liebrecht Prize was first awarded by the Faculty in December 1999 for outstanding doctoral or diploma theses. The purpose of the prize is to honor particularly dedicated and motivated students or former students of the Faculty of Mathematics and Natural Sciences at the University of Cologne who have delivered especially meritorious achievements in their academic master’s or doctoral theses. Typically, two prizes are awarded each year. The prize is based on a generous endowment by Mr. Dipl.-Ing. Klaus Liebrecht from the year 1998.
