Superconducting Quantum Interference Detectors

A superconducting quantum interference detector formed by two parallel Josephson junctions. 

Magnetic field detectors (superconducting quantum interference devices or SQUIDS). 

All electric currents are accompanied by magnetic fields. With the invention of the Superconducting Quantum Interference Device as an extremely low magnetic field (10 T) detector, it has become possible to measure the magnetic fields from the small endogenic currents of the body, even from the small sources in the heart and the central nervous system. This has opened up a whole new field of measurements analogous to their electric counterparts MKG (EKG), MEG (EEG), and so on. However, these interesting subjects are outside the scope of this book, and the reader is referred to the book by Malmivuo and Plonsey (1995). 

The most sensitive instruments are SQUID magnetometers (Fig. 1) which in general allow to measure signals down to a range of 10 emu. They are equipped with superconducting pickup coils and a superconducting quantum interference device as flux detector. 

SQUID Acronym for a superconducting quantum interference device SQUIDs are supersensitive superconducting detectors of extremely weak magnetic fields, hence their use in magnetometers and interferometers. 

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