Japan eyes quantum sub-hunting drone sensors as China extends undersea reach

Japan is considering the development of quantum sensor technology for drones that can detect submarines, as part of a larger undersea competition with China, the United States and their allies in the Indo-Pacific region. Released in late August, Japan's defense budget request for fiscal 2027 includes funding for research into a smaller, more advanced quantum magnetic sensor.

This technology would use atomic properties to detect minute changes in magnetic fields, potentially revealing the presence of a submarine. The sensor would be mounted on low-cost drones that fly near the sea surface and operate from warships. The goal is to make this technology available by 2031. Japan's defense ministry aims to develop the sensor, which would be used to detect Chinese submarines as they pass through strategic straits to reach the Pacific Ocean.

While magnetic sensors currently have limited detection range, using them on multiple unmanned systems could provide cost-effective persistent coverage. China has also been actively pursuing quantum magnetic sensor technology, testing a drone-mounted system last year. The United States and its allies are investing in similar detection and attack systems, with partnerships such as Aukus focusing on developing payloads and supporting systems for unmanned underwater vehicles.

As China continues to expand its submarine fleet, the competition to detect and track opposing undersea forces is intensifying. Retired Australian vice-admiral Peter Jones emphasized the importance of data processing in conjunction with sensors, as computers can combine weak signals to reveal valuable information.