Superconducting Quantum Interference Device (SQUID)

A Superconducting Quantum Interference Device (SQUID) is a highly sensitive instrument that detects extremely small magnetic fields. It uses superconductors—materials that conduct electricity without resistance when cooled to very low temperatures—and tiny loops with special junctions called Josephson junctions. When a magnetic field passes through the loop, it causes a change in the electrical current, which the SQUID can measure with extraordinary precision. Because of this sensitivity, SQUIDs are used in medical imaging, geophysical studies, and fundamental physics research to detect faint magnetic signals that other devices cannot pick up.