Physicists at Saarland University have developed magnetic field sensors that are breaking sensitivity records and opening up a whole range of potential new applications, from non-contact measurements of the electrical activity in the human heart or brain to detecting ore deposits or archaeological remains deep underground. Professor Uwe Hartmann and his research team have developed a system that allows them to detect weak magnetic signals over large distances in normal environments (no vacuum, no low temperatures, no shielding), despite the presence of numerous sources of interference. Their system can detect signal strengths far below a billionth of a tesla—about a million times smaller than the Earth’s magnetic field—and can be used to detect biomagnetic signals in the human body or geophysical phenomena.