Quantum Submarine Detector

Recent reports indicate that China may have made a breakthrough in designing a magnetometer capable of detecting submarines at much greater distances than is currently possible. The device would greatly enhance China’s anti-submarine capabilities in the highly disputed South China Sea.

Magnetic anomaly detectors (MADs) have been used by the military for decades to detect small changes in the earth’s magnetic field, which can be caused by large metal objects (such as submarines). But because magnetic fields decrease as the inverse cube of distance, the sub must be very close to the measuring device (i.e., within a few hundred meters) to be detectable.

The development of superconducting quantum interference devices (SQUIDs) allowed for much smaller magnetic disturbances to be sensed, but their increased sensitivity makes them highly susceptible to noise. As a result, SQUIDs are generally used for measuring minute biomagnetic fields under controlled conditions.

The new detector utilizes an array of SQUIDs that cancels out noise by comparing multiple readings. As an airborne system, it would be capable of detecting submarines at an estimated range of up to six kilometers. Combined with China’s “Great Underwater Wall” of submerged sensors and drone subs, the SQUID magnetometers would greatly extend their offshore surveillance capability.