First experimental generation of 148.4 nm CW VUV laser light via cavity-enhanced SHG in BaMgF4 crystal, yielding 16 pW output power.
A thorium-229 optical nuclear clock with feedback loop
4 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
The laser-accessible nuclear transition in the thorium-229 isotope has been identified as a promising candidate for the realization of an optical nuclear clock. Such a nuclear clock might rival or outperform current optical clocks based on electron-shell transitions in atoms or ions, is expected to be more robust against external perturbations, and provides enhanced sensitivity in clock-based tests of fundamental principles of physics. Here, we implement a thorium-229 nuclear clock by stabilizing a continuous-wave laser to the 148 nm nuclear transition with rapid feedback based on continuous absorption spectroscopy. The thorium-229 nuclei are embedded into a millimeter-sized, room temperature calcium fluoride crystal. A subharmonic of the 148 nm radiation is continuously compared to a Yb+ single-ion clock. The nuclear clock shows a simple shot-noise limited scaling of the fractional frequency instability of $3\cdot 10^{-12} \sqrt{\tau/\text{s}}$ where $\tau$ is the averaging time, approaching $10^{-15}$ instabilities over 1 day of continuous operation. Improvements of the instability by several orders of magnitude can be projected for future solid-state nuclear clocks. We use the nuclear clock to constrain models of ultralight dark matter by searching for periodic fluctuations and slow drifts in the nuclear transition energy, on time scales between 20 s and 1 day. Drawing benefit from the enhanced sensitivity of the thorium-229 transition, these constraints compete with the best atomic clocks concerning dark matter coupling to photons and go beyond previous measurements regarding coupling to the strong force and quarks.
years
2026 4representative citing papers
Demonstration of record conversion efficiency for a 148 nm VUV frequency comb using 16th-harmonic generation in a bulk-grown QPM crystal.
A review of 229Th isomer spectroscopy, clock platforms, nuclear-structure models, and fundamental-physics applications, with an additional mean-field check of the octupole minimum.
Colloquium overview of Th-229 nuclear clock development, covering its nuclear physics basis, recent direct laser excitation, clock design and systematics in traps and solids, and sensitivity to fundamental constant variations.
citing papers explorer
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Generation of continuous-wave laser light at 148.4 nm using cavity-enhanced second harmonic generation in $BaMgF_4$
First experimental generation of 148.4 nm CW VUV laser light via cavity-enhanced SHG in BaMgF4 crystal, yielding 16 pW output power.
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Record nonlinear conversion efficiency in the production of high spectral purity vacuum ultraviolet laser at 148 nm
Demonstration of record conversion efficiency for a 148 nm VUV frequency comb using 16th-harmonic generation in a bulk-grown QPM crystal.
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The $^{229}$Th Isomer: Nuclear Structure, Clocks, and Tests of Fundamental Physics
A review of 229Th isomer spectroscopy, clock platforms, nuclear-structure models, and fundamental-physics applications, with an additional mean-field check of the octupole minimum.
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Colloquium: Nuclear clocks
Colloquium overview of Th-229 nuclear clock development, covering its nuclear physics basis, recent direct laser excitation, clock design and systematics in traps and solids, and sensitivity to fundamental constant variations.