Flux periodicity in a complex superconducting network

A basic feature of superconductors is flux quantization, which leads to periodicity of superconducting parameters with magnetic field. This periodicity is crucial for understanding basic concepts, such as elementary charge, symmetry of the order parameter, etc. In quantum circuit applications the periodicity is utilized for maximizing design performance. These applications rely on the fact that the periodicity is well defined for a given superconducting structure. We use scanning SQUID imaging and numerical simulations to show that, in realistic nanoscale devices, the periodicity depends on the temperature and the actual geometric details of the structure, specifically, the width of the wires that define the superconducting network. This should be taken into account in any experiment or application based on complex superconducting structures.