This is an overview of all the research projects I have worked on in chronological order. I will reference papers that have resulted from those projects. Please also have a look at my Google scholar account to get a slightly more up-to-date overview of my publications.
January 2025 - present
In 2025 I joined Prof. Dmitri K. Efetov's group as a PostDoc to work on various projects surrounding Twisted Bilayer Graphene (TBG). The focus of my work lies on the recent invention of the Quantum Twisting Microscope (QTM), and its extension to measurements at cryogenic conditions in a dilution refrigerator. In terms of material candidates, I am particularly interested in systems that show strong interactions and topologically non-trivial band structures.
May 2021 - January 2025
For my PhD, I studied the Fermi surface of (quasi) one-dimensional Dirac (nodal-line) semimetals via quantum oscillations and Density Functional Theory (DFT) calculations under the supervision of Prof. F. Malte Grosche.
Quantum oscillations, often observed as oscillations in the magnetization or resistivity of a material in a strong magnetic field at low temperatures, provide a powerful means to probe the Fermi surface. The quantum oscillations arise from the quantization of electron orbits in the presence of a magnetic field and carry valuable information about the Fermi surface geometry and electronic structure. Particularly, the non-trivial Berry phase shift and the light effective masses are characteristic for topological materials.
My work focused mostly on the (double) Dirac semimetal candidate NbTe4, and the Dirac nodal-line semimetal candidates TaNiTe5 and TaPtTe5. Besides growing these crystals, I performed low-temperature measurements in strong magnetic fields (up to 15T) to gain insights into the electronic structure of these materials. This work was supported with standard transport measurements and DFT calculations.
Some of my results can be found on the arXiv. A number of other papers are in the making and will be included on this page soon. I presented some of my results in talks at the APS March Meeting 2024 and at the DPG March Meeting 2024.
August 2022 - October 2022
Driven by my previous work on Majorana fermions, I started working on skyrmion textures in thin magnetic films and their interaction with vortices in s-wave superconductors during my PhD. Theoretically, these interactions are predicted to host Majorana excitations, but would provide a platform that makes it much easier to perform braiding operations, which is crucial for the application of quantum gates. This is an advantage compared to the one-dimensional nanowires that e.g. Microsoft is working on.
Prof. Jürgen Weis at MPI invited me to use his state-of-the-art nanostructuring lab. Bulk crystals of Fe3GeTe2 were grown via chemical vapor transport (CVT) and wafers with thin films of NbN were prepared using atomic layer deposition (ALD). The van der Waals material Fe3GeTe2 could then be exfoliated onto the NbN chips inside a glove box, and the dimensions of the resulting flakes would then be determined with atomic force microscopy (AFM) and scanning electron microscopy (SEM). For further processing, electron beam lithography is used to create a mask for the Hall bars on top of the flakes, and plasma etching was used to etch the corresponding Hall bars. These samples were then taken to Cambridge for further transport measurements.
September 2020 - March 2021
After learning about the toric/surface code during my studies and inspired by the more general interplay between topological phenomena and quantum computing, I wrote my Master's thesis in Gabriel Aeppli's group which examines the interaction of superconductor-semiconductor interfaces. This project was part of a collaboration with Microsoft and aimed at understanding topological superconductivity that will ultimately help the discovery of Majorana fermions.
We used angle-resolved photoelectron spectroscopy (ARPES), photon energy dependent core level spectroscopy, and self-consistent electronic structure calculations to determine critical parameters for engineering quantum devices: band offset, band bending profile, and the number of occupied quantum well subbands of interfacial accumulation layers at semiconductor-metal interfaces. The band alignment of these interfaces is difficult to predict theoretically, and thus experimental measurements are needed to reliably determine their properties. My work was about band alignment of InAs(111)B/Pb epitaxial interfaces, which have recently gained interest for their potential in topological quantum computing. Besides working on the measurements, I was involved in data analysis, for which new methods had to be developed to improve accuracy. Since the band offset is one of the most important parameters for the simulation of topological phase diagrams of Majorana-zero-modes in semiconductor nanowires, my work will become a crucial tool for the targeted design of topological quantum bit devices.
Our paper will soon be submitted to IOP – Semiconductor Science and Technology.
June 2019 - September 2019
During my undergraduate degree, I spent a summer at Harvard in Prof. Eugene Demler's group, constructing an effective model of a THz cavity on the surface of a paraelectric material by analyzing instabilities in the system. THz cavities have a width much smaller than the wavelength of electromagnetic radiation in vacuum and can be used to create a local ferroelectric transition, with many potential applications in experiments. To solve this problem, my advisor and I tried various approaches from condensed matter field theory, for which I provided most of the numerical work. The latter included diagonalizing Hamiltonians which had to be done on the FAS Research Computing cluster due to their complex structure. Moreover, I delved into the literature to support our analysis and to overcome some issues we encountered.
My work contributed to the findings in this and that publication, where it was acknowledged.
February 2019 - May 2019
During my year at MIT, I had the opportunity to work in plasma physics in Prof. Loureiro's group. Based on a previous paper that the professor published, I was responsible for verifying selected theoretical results by simulating electron-positron (pair) plasma turbulence in the sub-relativistic, strongly magnetized, low-beta regime. In particular, I was asked to confirm some predictions about the scaling of various spectra in the kinetic range. While working very closely with my advisor and the professor for around nine months, I ran simulations on a computer cluster with various parameters and discussed the results to decide about what direction to head next. Furthermore, I was supposed to write diagnostics that extract information from the simulation results and help drawing conclusions about the plasma. In my work, I made use of diagnostics that were developed in the past for other projects and in some cases, needed to be rewritten and made more efficient.
This work was published in Physical Review Letters. The arXiv version of the paper is also available.
December 2018 - March 2019
Quantum key distribution (QKD) is a method of secure communication that utilizes principles of quantum mechanics to exchange cryptographic keys between two parties. The key purpose of QKD is to enable the creation of a shared secret key between two parties in a way that is theoretically secure against any kind of computational attack, even by a quantum computer.
At MIT, I had the opportunity to work in theoretical quantum information processing with Prof. David Kaiser and Prof. Joseph Formaggio. Our project aimed to find a way to jam a quantum key transmission system by rotating the polarization of photons in such a way that the Bell test, which is currently used in quantum key distribution to detect eavesdropping, would give inconclusive results about whether the transmission network has been hacked. In combination with other attacks, this could become a useful tool for extracting information from a QKD network. I performed various calculations on this project, among which I gave a theoretical derivation of the effect that the rotation of the polarization of a photon has on the violation of Bell's inequality.
This work was published in Quantum Information and Computation. The arXiv version of the paper is also available.