China’s race to build next-generation military and scientific systems has taken another turn beneath the surface of the Pacific Ocean. Researchers linked to the Chinese Academy of Sciences say they have produced a crystal capable of generating ultraviolet light at 145.2 nanometres, crossing a technical barrier that scientists have struggled with for years in the pursuit of thorium nuclear clocks. While the announcement emerged from a physics laboratory in Xinjiang, the discussion surrounding it has quickly moved into naval warfare, submarine stealth and the changing balance of undersea military power.
At the centre of the development is a problem that has haunted submarine fleets since the Cold War. Submarines can remain hidden underwater for long periods, but their ability to know exactly where they are becomes weaker the longer they stay submerged. Satellite navigation systems such as GPS do not work underwater, forcing submarines to periodically surface or rise close enough to the surface to update their position. Those moments create opportunities for detection through radar, aircraft surveillance, satellites and electronic monitoring.
Chinese researchers now believe nuclear clocks based on thorium-229 could reduce that problem dramatically. If successful, submarines may eventually maintain highly accurate positioning without needing external navigation updates for long periods. For military planners, that possibility carries consequences that stretch well beyond laboratory physics.
The breakthrough announced this month came from a team led by scientist Pan Shilie at the Xinjiang Technical Institute of Physics and Chemistry. Their newly developed fluorinated borate crystal produces ultraviolet wavelengths shorter than previous materials could manage. That detail may sound highly technical, yet it addresses one of the biggest obstacles in developing thorium nuclear clocks.
Thorium-229 is unusual because its atomic nucleus can be activated by ultraviolet light at a very narrow wavelength near 148.3 nanometres. Scientists have spent years trying to create stable laser systems capable of reaching that target. Earlier materials, including potassium beryllium fluoroborate developed in China decades ago, came close but stopped near 150 nanometres. The new crystal reportedly crosses that threshold for the first time.
The achievement matters because nuclear clocks operate differently from ordinary atomic clocks. Conventional atomic clocks track movements of electrons around an atom. Nuclear clocks instead measure activity inside the nucleus itself. Since the nucleus is less affected by heat, vibration and electromagnetic disturbance, scientists believe nuclear clocks could become vastly more stable than current systems.
That level of precision matters for navigation. Inertial navigation systems used by submarines rely on clocks, accelerometers and gyroscopes to estimate movement from a known starting point. Even small timing errors eventually create larger position errors over time. The more stable the clock, the less drift accumulates.
China’s submarine ambitions collide with a new timing race
China’s navy has expanded rapidly over the past decade, particularly in submarines and long-range naval operations. The People’s Liberation Army Navy now operates growing fleets of nuclear-powered attack submarines and ballistic missile submarines, including the Type 093 and Type 096 programmes. These vessels are expected to patrol wider areas of the Pacific while operating farther from Chinese coastal waters.
For the United States Navy, submarine tracking has long depended partly on predictability. During the Cold War, American anti-submarine warfare relied heavily on sonar networks, patrol aircraft, attack submarines and satellite monitoring. Yet navigation limits also shaped submarine behaviour. Submarines periodically needed opportunities to correct positioning data, creating patterns that tracking systems could exploit.
A nuclear clock system that reduces or delays those corrections could weaken some of those assumptions. Chinese submarines capable of remaining submerged longer without exposing antennas or surfacing for updates would present fewer opportunities for observation. Military analysts say that matters especially around Taiwan and the wider Indo-Pacific region, where naval surveillance activity has intensified steadily in recent years.
The timing of the announcement also reflects a wider scientific competition unfolding quietly between major powers. China is not alone in researching nuclear clocks. American and European laboratories are pursuing similar work, partly because of military interest and partly because ultra-precise clocks could affect communications, space travel and scientific measurement.
China’s research effort now stretches across several universities and laboratories. Earlier this year, the University of Science and Technology of China announced progress on an optical lattice clock said to lose only one second over tens of billions of years. Tsinghua University has also worked on ultraviolet laser systems linked to thorium research.
This broader national effort shows how China increasingly approaches advanced science through long-term state-backed programmes rather than isolated laboratory projects. Quantum research, semiconductor production, hypersonic weapons and artificial intelligence have all received similar treatment. Nuclear clocks now appear to be joining that list.
Yet major hurdles still stand between laboratory success and military use. Producing ultraviolet light inside controlled experiments is very different from installing nuclear clock systems inside operational submarines. Military hardware must survive vibration, pressure changes, temperature variation, saltwater exposure and long deployments at sea.
Miniaturisation also remains a major issue. Laboratory clock systems are often large, delicate and power-intensive. Submarine systems would require compact designs capable of functioning continuously inside harsh naval environments. Reliability matters as much as accuracy in military systems. A navigation device that fails under operational stress becomes a liability rather than an advantage.
The wider military contest is moving underwater
The growing interest in navigation independence reflects how warfare itself is changing. Military planners increasingly worry about what happens when satellite systems fail during conflict. GPS networks can be jammed, disrupted or attacked. Electronic warfare now targets communications, radar and positioning systems as heavily as traditional weapons target ships or aircraft.
China has invested heavily in reducing dependence on outside systems. Satellite navigation through the Beidou network, quantum communication research and underwater sensing programmes all form part of a wider attempt to reduce military vulnerability during conflict. Nuclear clocks fit naturally into that effort because they could allow submarines and missiles to operate with less reliance on external positioning updates.
For the United States Navy, undersea warfare has long been one of its strongest military advantages. American submarines remain among the quietest and most advanced in the world, while anti-submarine surveillance networks remain extensive across the Pacific. Yet Washington increasingly faces pressure from Chinese naval growth and technological investment.
The concern is not that China suddenly gains total submarine superiority from one scientific breakthrough. Military balances rarely change that quickly. Instead, the concern is cumulative. Improvements in navigation, stealth, underwater communication and autonomous systems together could slowly narrow advantages that Western navies held for decades.
Precise navigation also affects weapons systems. Cruise missiles, hypersonic weapons and long-range strike systems all depend heavily on accurate timing and positioning. A submarine capable of maintaining exact location data without outside help may launch weapons more effectively during electronic disruption or satellite outages.
Researchers also see civilian uses for nuclear clocks. Deep-space probes, long-distance exploration missions and scientific measurement systems may all benefit from more accurate timing. Yet as often happens with advanced science, military interest arrives quickly when new capabilities emerge.
