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Detection of Second-order Topological Superconductors by Josephson Junctions

Speaker:Dr. Song-Bo Zhang
Affiliation:Institute for Theoretical Physics and Astrophysics, University of W├╝rzburg
Date:September 5, 2019 (Thursday)
Time:4:00 p.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU


Second-order topological superconductor (SOTS) is a generalization of topological superconductors and characterized by localized Majorana corner states. One promising candidate system of SOTS is the quantum spin Hall insulator in proximity to an unconventional superconductor. In this talk, I will talk about Josephson junctions based on SOTS. I will show that tuning the chemical potential in the superconductor strongly modifies the pairing gap of the helical edge states and leads to topological phase transitions. As a result, the supercurrent in the Josephson junction is controllable and a 0-π transition is realized by tuning the chemical potentials in the superconducting leads. I will also show that these striking features are stable in junctions with different sizes, doping in the normal region, and in the presence of disorder. Thus, we can use them as novel experimental signatures of the second-order topological superconductor. Finally, I will talk about the Majorana bound states in the Josephson junction, and propose the 0-π transition as a fully electric way to create or annihilate Majorana bound states without magnetic manipulation.

[1] Song-Bo Zhang and Björn Trauzettel, arXiv:1905.09308

Coffee and tea will be served 20 minutes prior to the seminar.

Anyone interested is welcome to attend.