Trapping a single vortex and reducing quasiparticles in a superconducting resonator

Area of Science:

• Condensed Matter Physics
• Superconducting Devices
• Microwave Engineering

Background:

• Vortices in thin-film superconductors affect device performance.
• Understanding vortex dynamics is crucial for superconducting microwave resonator applications.

Purpose of the Study:

• To investigate the impact of a single trapped vortex on superconducting microwave resonator performance.
• To analyze vortex influence on quality factor and resonant frequency based on location.

Main Methods:

• Utilized a variable-linewidth geometry for a weakly coupled superconducting resonator.
• Employed field cooling to trap a single vortex.
• Analyzed resonator performance for modes with vortex near current antinodes and nodes.

Main Results:

• A single vortex near a current antinode decreased the quality factor and shifted the resonant frequency.
• A vortex at a current node caused no excess loss and increased the quality factor.
• Observed enhancement attributed to reduced nonequilibrium quasiparticles near the vortex core.

Conclusions:

• The precise location of a trapped vortex critically determines its effect on resonator performance.
• Vortex trapping can be engineered to enhance, rather than degrade, resonator quality factor.
• Findings offer insights for designing advanced superconducting microwave devices.