Karen Bayros, RMIT
Josephson junctions are key elements of quantum computers based on superconducting qubits. Although superconducting qubits are one of the most promising candidates to realise large-scale quantum computing, the materials science of Josephson junctions still limits their performance. Imperfections in Josephson junctions are thought to be a source of dissipation, decoherence, parameter drift, and uncertainty. As an example, inhomogeneities in the barrier thickness can result in a non-ideal current-phase response.
Using molecular dynamics and a tight-binding description, we develop a numerical model of Al/AlOx/Al Josephson junctions to investigate the influence of atomic structure on the electrical response of these junctions. Pairing this with a non-equilibrium Green’s function (NEGF) approach to study transport, we find that the disordered nature of the oxide barrier results in regions with higher transparency which can facilitate quasiparticle current flow through the barrier. These models will help improve the design and fabrication of superconducting qubits.
About the presenter
Karen Bayros is a PhD student working with Jared Cole and Jackson Smith at RMIT where she models current flow through dielectric barriers in superconducting quantum bits. The influence of defects and imperfections can limit the dissipationless flow-through devices comprised of these barriers, and Karen uses advanced computational models to understand the interplay between the molecular structure and the electrical response, within FLEET’s Research theme 1: topological materials.