Researchers locate optimal crystal site for ultra-precise nuclear clock
Physicists have identified a crystal position where thorium-229 atoms can function as a nuclear clock with unprecedented accuracy.
In a new study published in Science, Thorsten Schumm and collaborators at Vienna University of Technology identified four lattice sites where thorium-229 atoms can reside in calcium-fluoride crystals, discovering that only one site yields a single-wavelength response indicating a homogeneous electric field suitable for a nuclear clock. The isotope’s unusually low nuclear transition energy allows excitation with ultraviolet light, avoiding the need for unattainable gamma-ray lasers.
After fifteen years of crystal-growth experiments, the team produced transparent millimeter-scale crystals doped with thorium-229 and demonstrated the clock’s principle using a custom UV laser pulse sequence. Independent researchers at Tsinghua University, led by Shiqian Ding, have achieved similar performance with a higher-power laser and lower thorium concentration. Both groups have constructed early prototypes and filed patents for chip-compatible designs, with the goal of moving from lab-size to shoebox-size units that could support critical timing in data-center servers.
Why it matters
A compact, ultra-precise nuclear clock could vastly improve timekeeping for communications, finance and navigation systems.
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