Japan plans submarine-detecting quantum sensors for aerial drones amid Indo-Pacific undersea competition

Feeling the pinch from cost and personnel pressures, Tokyo’s defence planners aim to unlock potential in uncrewed systems

Japan is looking to develop submarine-detecting quantum sensors for aerial drones, the latest move in a growing undersea competition pitting China against the United States and its allies across the Indo-Pacific.

Released in late August, Tokyo’s defence budget request for fiscal 2027 includes research into a smaller, more capable quantum magnetic sensor, a technology that uses the properties of atoms to detect tiny changes in magnetic fields that could reveal a submarine.

The project is one of numerous initiatives submitted ahead of Japan’s planned year-end security strategy revisions, with funding to be decided during budget compilation.

The Nikkei newspaper reported on Thursday that the defence ministry aimed to develop the sensor by fiscal 2031. It would be mounted on low-cost drones flying near the sea surface and operating from warships.