Axion Electrodynamics of Superconductor-Topological Insulator Heterostructures

• Applicant: Privatdozent Nicola Poccia, Ph.D.
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460444718

Josephson junction-based structures offer not only an opportunity to probe fundamental quantum phenomena, they may be used as quantum devices capable of performing tasks not possible in standard, semiconducting based electronics. One example is provided by qubits, which can be created and manipulated by Josephson junction devices. The prime goal of this proposal is to experimentally realize a platform to detect and control collective effects in new types of topological Josephson effects involving type-II superconductors, where three-dimensional topological insulators are used as tunnel junctions. In order to address the material science challenges, as well as to investigate the novel transport properties and develop the technology for phase-biased topological Josephson electronics, we propose a novel experimental platform based on an array of superconducting islands. We will explore the vortex system in a proximity array of superconducting islands, which by virtue of the correspondence between statistical physics and quantum mechanics, mimics the behavior of the electronic systems in atomic lattices. As an exemplary phenomenon, we will focus on dynamical (i.e. current-driven) Mott insulator-to-metal transitions in systems with different symmetries and their instabilities. Finally, the proximity effect with a three-dimensional topological insulator substrate will be driven by the fabrication of a superconducting-topological insulator-superconducting vertical Josephson junction, representing a quite unique device by itself. We will tune the superconducting phases of the superconducting islands to observe for the first time the theoretically predicted anyons, quasi-particles exhibiting fractional quantum statistics, via a measurement of the Josephson-Witten effect.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Artur Philipp Nikolaus Erbe