Recent years nanoelectronics research focuses in low dimensional hybrid nanostructures. When nanowires or two dimensional sheets are connected to magnetic or superconducting structures novel device concepts appear. One of the driving motivations of the field is to engineer quantum bits which combined together could lead to quantum computing architectures. At the moment several different platforms are investigated where quantum bits can be realized. One of the promising ones, called Andreev qubit is a special combination of spin and superconducting qubits. It is expected to bring the best of both worlds including long coherence times and electrical manipulation.

Andeev qubits are based on Andreev levels which form when a superconductor is coupled to the non-superconducting nanosystems. These levels are responsible for the so-called proximity effect and for supercurrents flowing through superconductor-normal-superconductor heterojunctions. First steps towards qubit operations in semiconducting nanowires have been shown, where manipulations have been done using high frequency techniques.

During the PhD work the candidate will study Andreev levels in low dimensional systems and couple them to high frequency readout circuits. The circuits will be realized using electron-beam lithography and will be measured at ultra-low temperatures. The work is done in close collaboration with European universities.

Left: Andreev qubit architecture from TU Delft (PRL. 121, 047001, 2018). Right:Andreev levels in a quantum dot (source: G. Fülöp, Sz. Csonka)