Extra Seminar - Würzburg ToCoTronics Colloquium

Josephson junctions play a central role in our understanding of superconductivity and in the development of quantum circuits. In their original formulation, they consist of two superconductors separated by a thin insulating barrier. This picture can be significantly enriched by replacing the insulator with more complex materials  [1], including conducting systems with internal structure.

This broader class of junctions enables both the engineering of tailored superconducting devices and the possibility of locally perturbing the supercurrent within the non-superconducting region. In this talk, I will explore how local perturbations, such as gates or probe-induced potentials, affect Josephson transport in a variety of platforms, including two-dimensional topological insulators, spin–orbit coupled InAs nanostructures, and graphene [2,3].

I will show that local probes provide a powerful tool to control superconducting transport, leading to phenomena such as the renormalization of the supercurrent, non-reciprocal Josephson effects, the emergence of Andreev molecules, and even chaotic supercurrent behavior. Altogether, these findings highlight how local perturbations can both enrich the physics of Josephson junctions and provide a versatile route to control superconducting transport.

[1] K. A. Pitton, et al., arXiv:2603.17921 .
[2] S. Fracassi, et al., Appl. Phys. Lett. 124, 24 (2024).
[3] A. Lombardi,  et al., Commun. Mater. 6 (1), 272 (2025).