A Chinese Navy submarine attends an international fleet review to celebrate the 60th anniversary of the founding of the People's Liberation Army Navy on April 23, 2009 off Qingdao in Shandong Province. Photo by AFP

Modern navigation systems rely on time-based calculations, in which devices such as smartphones determine location by receiving satellite signals and measuring how long they take to arrive. This data is then used to triangulate position, meaning higher clock precision leads to greater accuracy.

However, GPS systems can be jammed or spoofed with fake signals and do not function effectively underwater or underground, according to Interesting Engineering. For submarines, this presents a major limitation, as they must surface to obtain GPS signals, increasing their exposure to detection.

To reduce this risk, submarines use atomic clocks, which measure time based on electron vibrations around atoms. While highly accurate, scientists believe nuclear clocks, which rely on vibrations within atomic nuclei, could be 10 to 1,000 times more precise.

A research team led by Pan Shilie at the Xinjiang Technical Institute of Physics and Chemistry focused on Thorium-229, an isotope whose nucleus vibrates at unusually low energy levels, making it suitable for next-generation timekeeping.

Measuring these vibrations requires extremely precise ultraviolet lasers with wavelengths around 148.3 nanometers, which are difficult to produce. The newly developed fluorinated borate crystal addresses this challenge by generating ultraviolet light at a record 145.2 nanometers, meeting a key requirement for nuclear clock systems under development globally, including in the U.S.

The findings, reported in the journal Advanced Materials and cited by the South China Morning Post, surpass previous benchmarks set by potassium beryllium fluoroborate, a material developed in China in the 1990s that could only reach about 150 nanometers.

Researchers said the new crystal also delivers several times higher conversion efficiency than standard materials, allowing more input laser energy to be converted into the required ultraviolet light, improving overall system performance.

Yang Zhihua, a co-author of the study, said the work provides a more systematic method for designing such materials, moving beyond trial-and-error approaches. If produced reliably at scale, the crystal could help shrink nuclear clock systems from laboratory setups into compact devices suitable for real-world applications.