A dual-function superconducting shield for SQUID (superconducting quantum interference device) gradiometers

In this work, we design and experimentally validate a novel dual-function superconducting shield that protects the Superconducting Quantum Interference Devices (SQUIDs) from external magnetic interference through superconducting shielding, while allowing compensation of pickup-coil imbalance by finely adjusting its axial displacement. A prototype low-temperature SQUID gradiometer with a 150 mm baseline and a 105 mm2 coil area was fabricated and tested. Intrinsic noise measurements indicate a noise level of ∼50 fT/m/√Hz at 0.1-1 Hz, while dynamic tests on a moving platform confirm stable operation under strong magnetic disturbances. The dual-function shield provides a practical solution that enhances the stability and reliability of wire-wound SQUID gradiometers for practical applications.