SFB Colloquium

Second-order topological superconductor (SOTS) is a generalization of topological superconductors and characterized by localized Majorana corner states which are two dimensions lower than the bulk. Recently, the SOTS phase has been predicted in several realistic systems and attracted intense interest. One promising candidate system of SOTS is the quantum spin Hall insulator in proximity to an unconventional superconductor. However, the detection and transport properties of SOTS are still rarely explored. In this seminar, I will talk about SNS Josephson junctions based on the SOTS. I will show that tuning the chemical potential in the superconductor strongly modifies the pairing gap of the edge states and leads to topological phase transitions. As a result, the supercurrent in the junction is controllable and a 0-π transition can be realized by tuning the chemical potentials in the superconducting leads. I will also show that these striking features are robust in junctions with different sizes, doping in the normal region, and in the presence of disorder. Thus, we may use them as novel experimental signatures to detect the SOTS. Finally, I will discuss the Majorana bound states in the junction, and propose the junction with such a 0-π transition as a fully electric platform to generate and manipulate Majorana bound states.