«Detecting small metallic contaminants in food via magnetization: A practical metallic - contaminant detecting system using three high - Tc RF superconducting quantum interference devices (SQUIDs).» (sciencedaily.com)
(for superconducting quantum interference devices) are the most sensitive detectors of magnetic fields. (scientificamerican.com)
The «mirror» consists of a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. (religion.blogs.cnn.com)