A SQUID consists of a superconducting loop with one or more Josephson junctions, which are weak links between superconductors. When an external magnetic field is applied, it induces a current in the loop. Due to the quantum mechanical properties of the superconducting state, the current that flows through the Josephson junctions exhibits quantum interference, resulting in a periodic voltage that can be measured. This voltage is directly related to the magnetic flux, allowing precise detection of magnetic fields.
