Что (кто) такое Squid - определение
![Electrical schematic of a SQUID where <math>I_b</math> is the bias current, <math>I_0</math> is the critical current of the SQUID, <math>\Phi</math> is the flux threading the SQUID and <math>V</math> is the voltage response to that flux. The X-symbols represent [[Josephson junction]]s.](https://commons.wikimedia.org/wiki/Special:FilePath/SQUID IV.jpg?width=200 "Electrical schematic of a SQUID where <math>I_b</math> is the bias current, <math>I_0</math> is the critical current of the SQUID, <math>\Phi</math> is the flux threading the SQUID and <math>V</math> is the voltage response to that flux. The X-symbols represent [[Josephson junction]]s.")
![The inner workings of an early SQUID, circa 1990<!-- seems to have been built after the [[National Bureau of Standards]] was renamed [[NIST]] in 1988. Much more primitive SQUIDS were built at NBS in the first half of the 1970s. -->](https://commons.wikimedia.org/wiki/Special:FilePath/Squid prototype.jpg?width=200 "The inner workings of an early SQUID, circa 1990<!-- seems to have been built after the [[National Bureau of Standards]] was renamed [[NIST]] in 1988. Much more primitive SQUIDS were built at NBS in the first half of the 1970s. -->")
Википедия
A SQUID (superconducting quantum interference device) is a very sensitive magnetometer used to measure extremely subtle magnetic fields, based on superconducting loops containing Josephson junctions.
SQUIDs are sensitive enough to measure fields as low as 5×10−14 T with a few days of averaged measurements. Their noise levels are as low as 3 fT·Hz−1⁄2. For comparison, a typical refrigerator magnet produces 0.01 tesla (10−2 T), and some processes in animals produce very small magnetic fields between 10−9 T and 10−6 T. SERF atomic magnetometers, invented in the early 2000s are potentially more sensitive and do not require cryogenic refrigeration but are orders of magnitude larger in size (~1 cm3) and must be operated in a near-zero magnetic field.
