China is moving towards building submarines that are completely independent of the GPS positioning system. Researchers from the Xinjiang Technical Institute of Physics and Chemistry have announced the achievement of a record wavelength of ultraviolet radiation of 145.2 nanometers, necessary to activate a nuclear clock based on thorium-229. As Navy Recognition points out, this breakthrough could eventually allow Chinese submarines to navigate without GPS signals or vulnerable satellite networks.
For the Pentagon and the US Navy, this technology is a concern, since modern anti-submarine warfare partly depends on predicting the moment when submarines need to surface to synchronize navigation systems. Modern submarines use inertial navigation combined with periodic adjustments based on satellite data to maintain accurate positioning. GPS signals cannot penetrate seawater, which forces submarines to periodically surface or deploy masts near the surface to calibrate navigation data.
Multipurpose submarine "Type-093", China
H I Sutton
Such moments create vulnerabilities that the US Navy exploits by using satellites, maritime patrol aircraft, electronic reconnaissance and attack submarines. If Chinese submarines equipped with nuclear clocks can maintain high-precision positioning for long periods of time without being connected to external sources, they will be able to stay underwater for longer, significantly reducing detection capabilities.
Unlike conventional atomic clocks, which are based on the vibrations of electrons around the atomic nucleus, nuclear clocks measure energy transitions directly inside the nucleus itself. Since the core is much less sensitive to external influences such as temperature changes, radiation, or electromagnetic interference, nuclear clocks are theoretically 10-1000 times more accurate than modern atomic clocks.
China's key achievement is related to the fluoroborate crystal, which converts laser light into deep ultraviolet radiation with significantly greater efficiency than previous materials. The existing systems generated ultraviolet light with a wavelength of about 150 nanometers, while the nuclear excitation of thorium-229 requires about 148.3 nanometers. The new crystal has exceeded this threshold, reaching 145.2 nanometers, which potentially opens the way to the creation of a working nuclear clock based on thorium.
As Navy Recognition notes, the operational consequences for the Chinese People's Liberation Army (PLA) Navy can be significant. China's growing fleet, consisting of the Type-093 multipurpose submarines and the future Type-096 strategic submarines, is under increasing pressure from the US Navy's anti-submarine assets in the Indo-Pacific region.
Currently, the U.S. Navy has one of the world's most advanced underwater tracking systems, combining Virginia-class multipurpose submarines, P-8A Poseidon maritime patrol aircraft, bottom sonar systems, underwater sensor networks, aircraft carrier strike groups and space surveillance assets. Together, they are capable of detecting and tracking enemy submarines operating near Taiwan, in the South China Sea and in key areas of the Pacific Ocean.
If Chinese submarines become capable of GPS-independent navigation with near-perfect timing accuracy, they will be able to act more unpredictably. This will complicate American tracking operations and potentially weaken the established advantage of the United States in the confrontation under water.
