Chinese crystal ‘paves way’ for GPS-free thorium clock navigation

Scientists in Xinjiang have created the world’s first crystal that can produce the ultraviolet light needed for future thorium nuclear clocks, which could one day guide submarines and deep-space probes without GPS.
The fluorinated borate compound could push laser light to a record 145.2 nanometres (nm) – a wavelength short enough to meet a key requirement for these ultra-precise, portable clocks being developed in the United States, China and elsewhere, the team reported in Advanced Materials in…