Revealing Temperature-Dependent Noise Sources in Aluminum Oxide Josephson Junctions Using Topological Analysis

Abstract

Despite many improvements in the quality and reliability of Josephson junctions, the understanding of their noise sources, particularly the effect of oxidation parameters on the atomic arrangement of the interface and barrier layers, remains elusive. Here, we apply a Voronoi tessellation, a geometrically structural and topological analysis, to the amorphous barriers in aluminum oxide junctions. To enable this analysis, we perform million-atom molecular dynamics simulations to develop oxidation models at different temperatures. We find that the temperature introduces noise by changing the atomic compactness of oxides in the junctions. High-temperature oxidation aggravates the structural disorder and surface roughness of the barrier. This work will pave the way for illustrating the microscopic noise origin of amorphous oxides, which can transform our fundamental understanding of noncrystalline materials and qubit decoherence mechanisms.