Josephson junctions are the key components in superconducting qubits which provide the basis for quantum computing. Despite their importance, there are still gaps in our understanding of the causes of decoherence in Josephson junctions. This presents a big limitation to the performance and advancement of quantum computers. It has been shown that lower thicknesses of the oxide tunnel barrier may result in the formation of pinholes that cause excess current to move through the barrier. This in turn reduces the performance and reliability of devices made from these junctions. Employing a tight-binding approach, we create an atomistic three-dimensional model for Al-Ox-Al Josephson junctions which can describe pinhole formation for different oxide thicknesses. Pairing this with a non-equilibrium Green’s function (NEGF) approach we then investigate electron transport through Josephson junctions with different pinhole configurations to understand the consequences they have on the current through the device. This approach can be similarly applied to study the Josephson effect in other materials.
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.
