Quantifying Magnetic Flux Impact on the Performance of Superconducting Quantum Devices

Superconducting films form the foundation of superconducting quantum devices, where magnetic fields can act both as a source of loss and as a beneficial factor for device performance. In this work, we systematically investigate the influence of controlled magnetic fields on the RF properties of high-coherence qubits fabricated from niobium and tantalum. Using Helmholtz coils, well-defined magnetic fields are applied as the devices are cooled through their critical temperatures, enabling intentional flux trapping. The resulting variations in superconducting and microwave characteristics are quantitatively analyzed to reveal correlations between the magnetic environment and device performance. The findings demonstrate that, while magnetic flux can contribute to dissipation, under certain conditions it can also stabilize device behavior. These results provide new insights into flux-related mechanisms and suggest strategies for optimizing magnetic environments in next-generation superconducting quantum technologies.