1. Topic ID: 0583
  2. Research topic: Electronic transport and topological superconductivity in nanoscopic Josephson junctions
  3. Supervisor: dr hab. inż. Michał Nowak
  4. Supervisor’s email address: mpnowak@agh.edu.pl
  5. Abstract: The proposed topic deals with theoretical investigation of Josephson junctions created by embedding a nanoscale semiconducting link between two superconducting electrodes.

    In the last decade, the study of such hybrid nanostructures has become one of the most active research areas in mesoscopic condensed matter physics. The combination of the rich spin physics of a low-dimensional semiconductor and electron pairing provided by the superconductor allows revealing uncanny phenomena. This includes proximity-induced superconductivity, which allows the supercurrent flow through the semiconducting material or the appearance of elusive Majorana quasiparticles that can store topologically protected quantum information [see https://arxiv.org/pdf/1911.04512.pdf for a nice review].

    Within this project, we will investigate several key aspects of Majorana bound state formation and topological transition in Josephson junctions. We will establish the interplay between the topological/trivial edge modes and feasibility of inducing the topological phase by the magnetic field of arbitrary orientation, with a strong emphasis on explanation of orbital effects that can be crucial for determining the topological transition. We will consider junctions on nanoflakes—slabs of 2D semiconductor—where both topological and trivial edge modes can exist and study signatures of topological transition on experimentally accessible quantities such as supercurrent. We will also examine the applicability of realistic junctions for creating superconducting qubits. The student's work will be closely related to the ongoing experimental progress, as the research will be conducted in collaboration with experimental team of prof. Stefan Heun [http://web.nano.cnr.it/heun/].

    The PhD will be implemented under the SONATA BIS project "Topological nanostructures and their junctions" [https://www.ncn.gov.pl/sites/default/files/listy-rankingowe/2020-06-15vpaw/streszczenia/491073-pl.pdf]
  6. Research facilities: The research will be carried out in the theory team of ACMiN AGH, which actively collaborates with the theory group of Faculty of Physic and Applied Computer Science AGH and several theory and experimental teams from abroad.

    The research equipment available for the student will include local computational clusters, TeraACMiN supercomputer, the Prometheus supercomputer at ACK Cyfronet, and a personal laptop. We will use state-of-the-art numerical tools (including Kwant Python package) and a remote computational environment (Project Jupyter).

    Travel expenses, foreign visits, and an extra salary (4 000 PLN per month) for the PhD student will be covered by the NCN SONATA BIS project.
  7. Funding source: Subsidy + grant salary