Japan's Quantum Submarine Sensor Sees Several Thousand Meters at Best. Tokyo Will Put It on Cheap Drones and Crowd the Straits China Must Use.

Japan is looking to add quantum magnetic sensors to inexpensive drones to track Chinese submarines in the narrow waterways they must use to reach the Pacific. Tokyo’s fiscal 2027 defense budget request, published last month, funds research into a quantum magnetic sensor that could detect minute shifts in magnetic fields from submerged vessels. Nikkei Asia says Japan aims to develop the system by fiscal 2031 and mount it on low-cost drones operating near the sea surface from military ships. However, analysts cited by the South China Morning Post note quantum sensor ranges are limited, so drones would likely be deployed in high numbers around strategic straits. A retired Australian vice admiral estimated detection would be “several thousand meters or less.”