The combination of superconductivity and topology is a very active field of solid state physics. It has exciting predictions like the presence of exotic excitations so-called Anyons, which cannot be described by fermionic or bosonic statistics. Topological superconductivity also hold a great promise for future quantum technologies, since it could help to protect fragile quantum information from externall noises.
The goal of this PhD project is to build up simple model systems with the combination of nano-sized building blocks and superconductors, which have topological non-trivial character. We aim to build up a Kitaev chain from an array of artificial atoms coupled by superconductors. The simplest such a chain, the so-called poor man Majorana setup, contains two quantum dots coupled by a superconductor between. We have recently developed such a two-quantum-dot setup and showed the first signatures of its molecular state. Our goal is to investigate such so-called Shiba-molecules in detail. We plan to use finite bias spectroscopy and phase biasing of the molecule as well. The spectrum in the latter case will be explored by microwave frequency measurements or by implementing an on-chip high frequency source and detector, for which a parallel voltage-biased Josephson-junction planned to be used. After understanding the two-site-molecule in detail, we plan to extend it to longer chains.
In the PhD work the candidate will develop novel nano device concepts, fabricate nanochips with e-beam lithography, investigate the transport behaviour with dc and microwave frequencies at ultra-low T measurements. The work is done in close collaboration with in-house theoreticians and several European universities in the framework of an EU network.