What is a SQUID (Superconducting Quantum Interference Device)?

• Why we need ultra-sensitive magnetometers • The physics behind superconductivity and Cooper pairs • How Josephson junctions work • The operating principle of a DC SQUID • How SQUIDs convert magnetic flux into measurable voltage • Applications in brain imaging (MEG), materials science, geophysics, and quantum circuits • Current state-of-the-art SQUID technology • Challenges and ongoing research