SQUID

Definition

A SQUID (Superconducting Quantum Interference Device) is an extremely sensitive magnetometer used to measure very subtle magnetic fields, based on superconducting loops containing Josephson junctions.

5 Must Know Facts For Your Next Test

1. SQUIDs operate at cryogenic temperatures, usually achieved with liquid helium or nitrogen.
2. They leverage the quantum mechanical principle of flux quantization.
3. Josephson junctions in SQUIDs allow the supercurrent to tunnel through an insulating barrier between superconductors.
4. They are used in applications such as medical imaging (e.g., MRI), geophysical surveys, and fundamental physics research.
5. The sensitivity of SQUIDs can reach the order of femtoteslas, making them one of the most precise measurement tools available.

Review Questions

• What principle allows a SQUID to measure extremely subtle magnetic fields?
• How do Josephson junctions contribute to the function of a SQUID?
• List two practical applications of SQUID technology.

Related terms

Superconductor: A material that can conduct electricity without resistance below a certain temperature called the critical temperature.

Josephson Junction: A quantum mechanical device made up of two superconductors separated by a thin insulating layer, which allows supercurrent to pass through via tunneling.

Magnetometer: An instrument used for measuring magnetic forces, especially the Earth's magnetism.