- Atomic clocks promise accuracy far beyond existing atomic timekeeping systems
- Thorium 229 offers a rare path to practical nuclear timing
- Ultraviolet breakthrough reduces one of the toughest barriers in the development of nuclear clocks
A new crystal developed by Chinese scientists has broken the world record for converting ultraviolet light, bringing nuclear clock technology closer to reality.
The fluorinated borate compound pushes laser light to a wavelength of 145.2 nm, beating the previous benchmark of 150 nm set by a Chinese crystal from the 1990s.
This wavelength is suitably short to meet a key requirement for ultra-precise portable nuclear clocks being developed in the US, China and other countries.
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Nuclear clocks – a big upgrade to GPS
Atomic clocks keep time by using vibrations inside an atomic nucleus instead of electron vibrations used in atomic clocks.
Atomic nuclei are far more stable than electrons and less affected by temperature, external vibrations and magnetic fields, meaning that atomic clocks can be 10 to 1,000 times more accurate than today’s atomic clocks.
Such precision would enable navigation in places where GPS does not work, including deep space and underwater.
Submarines currently have to surface to get GPS fixes, making them vulnerable to detection – so an atomic clock could allow them to navigate freely underwater using dead reckoning based on speed, direction and elapsed time.
The research team, led by Pan Shilie of the Xinjiang Technical Institute of Physics and Chemistry, turned to thorium 229 for its work.
This element is special because its core vibrates at a very low energy level, making it relatively easy to monitor and measure.
But measuring it requires extremely precise UV lasers with wavelengths around 148.3 nm, which have been very difficult to produce.
The new crystal converts laser light to 145.2 nm, still short of the target but a big step forward.
The team wrote that its work “paves the way for the practical development of the thorium 229 atomic wall.”
If the magic number is ever achieved, the crystal could also help missiles become immune to navigational jamming, a wartime advantage.
For spacecraft, autonomous deep space navigation without ground-based corrections would become possible, and signals from stars, pulsars, and radio sources could also serve as navigational aids.
The work also offers a new way to design next-generation deep ultraviolet materials for various applications.
In theory, the extreme precision of nuclear clocks could enable far tighter network synchronization, potentially leading to faster internet speeds in future systems.
Such watches are unlikely to make GPS completely redundant, but will help reduce reliance on these systems if perfected.
GPS can be jammed or spoofed with false signals, making it vulnerable in wartime, and it doesn’t work well underwater or underground. A thorium atomic clock would solve all these limitations.
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