229Th ile senkronize edilmiş bir nükleer saat

Özet (abstract)

Abstract Atomic clocks have made time and frequency the most precisely measured quantities in physics, progressing from microwave standards that realize the SI second 1 to optical clocks with unprecedented precision 2 . A nuclear clock transfers the frequency reference from an electronic to a nuclear transition and the uniquely low-lying, laser-accessible, isomeric transition in 229 Th currently offers the most practical route to compact, robust timekeeping and sensitive tests of fundamental physics 3–8 . Realizing such a clock requires turning spectroscopy of the 229 Th nuclear resonance 9–17 into a stable discriminator for steering a traceable oscillator. Here we demonstrate a 229 Th nuclear clock by stabilizing a continuous-wave, narrow-linewidth 148.4 nm vacuum-ultraviolet (VUV) laser 18 to a resolved, weakly temperature-sensitive nuclear transition 17,19 in 229 Th:CaF 2 crystals 20–22 . A 10-μW VUV source generated by four-wave mixing in cadmium vapour 18,23,24 and phototube-based frequency modulation absorption readout provide a fast, high-signal-to-noise nuclear discriminator. The clock reaches a fractional frequency instability of $$5\times 1{0}^{-13}/\sqrt{\tau /{\rm{s}}}$$ 5 × 1 0 − 13 / τ / s for averaging time τ . Clock-transition frequencies measured in two independently fabricated crystals agree at the 10 −13 level and are consistent with previous VUV-comb measurements on other 229 Th:CaF 2 crystals 17 . These results establish laser-addressed nuclei as operational clock references and provide a reproducible solid-state platform for compact nuclear clocks, nuclear quantum sensors and precision tests of fundamental physics.

Yazarların özeti; kaynağından alınmıştır. Nature, 2026 · DOI ↗