Frequency ratio of the ${}^{229\mathrm{m}}$Th nuclear isomeric transition and the ${}^{87}$Sr atomic clock

Abstract

Optical atomic clocks${}^{1,2}$ use electronic energy levels to precisely keep track of time. A clock based on nuclear energy levels promises a next-generation platform for precision metrology and fundamental physics studies. Thorium-229 nuclei exhibit a uniquely low energy nuclear transition within reach of state-of-the-art vacuum ultraviolet (VUV) laser light sources and have therefore been proposed for construction of the first nuclear clock${}^{3,4}$. However, quantum state-resolved spectroscopy of the ${}^{229m}$Th isomer to determine the underlying nuclear structure and establish a direct frequency connection with existing atomic clocks has yet to be performed. Here, we use a VUV frequency comb to directly excite the narrow ${}^{229}$Th nuclear clock transition in a solid-state CaF${}_2$ host material and determine the absolute transition frequency. We stabilize the fundamental frequency comb to the JILA ${}^{87}$Sr clock${}^2$ and coherently upconvert the fundamental to its 7th harmonic in the VUV range using a femtosecond enhancement cavity. This VUV comb establishes a frequency link between nuclear and electronic energy levels and allows us to directly measure the frequency ratio of the ${}^{229}$Th nuclear clock transition and the ${}^{87}$Sr atomic clock. We also precisely measure the nuclear quadrupole splittings and extract intrinsic properties of the isomer. These results mark the start of nuclear-based solid-state optical clock and demonstrate the first comparison of nuclear and atomic clocks for fundamental physics studies. This work represents a confluence of precision metrology, ultrafast strong field physics, nuclear physics, and fundamental physics.

arXiv comment22 pages, 5 figures, 1 extended data figure

References in corpus (31)

• Direct Frequency Comb Spectroscopy in the Extreme Ultraviolet
• Optical clock intercomparison with $6\times 10^{-19}$ precision in one hour
• Resolving the gravitational redshift within a millimeter atomic sample
• High-energy pulse self-compression and ultraviolet generation through soliton dynamics in hollow capillary fibres
• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Energy of the ${}^{229}$Th nuclear clock transition
• A clock with $8\times 10^{-19}$ systematic uncertainty
• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• Observation of the radiative decay of the ${}^{229}\mathrm{Th}$ nuclear clock isomer
• Measurement of the ${}^{229}$Th isomer energy with a magnetic micro-calorimeter
• Performance of a 229 Thorium solid-state nuclear clock
• Quantum sensing with atomic, molecular, and optical platforms for fundamental physics
• X-ray pumping of the Th-229 nuclear clock isomer
• Extreme Ultraviolet Radiation With Coherence Time Greater Than 1 s
• Extreme Nonlinear Optics in a Femtosecond Enhancement Cavity
• Demonstration of a time scale based on a stable optical carrier
• Sensitivity of ${}^{229}$Th nuclear clock transition to variation of the fine-structure constant
• Energy of the ${}^{229}$Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference
• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• Radioluminescence and photoluminescence of Th:CaF${}_2$ crystals
• Controlling ${}^{229}$Th isomeric state population in a VUV transparent crystal
• Concepts for direct frequency-comb spectroscopy of ${}^{229\text{m}}$Th and an internal-conversion-based solid-state nuclear clock
• Coherence-enhanced optical determination of the ${}^{229}$Th isomeric transition
• Precision calculation of hyperfine constants for extracting nuclear moments of 229Th
• High-Precision Ramsey-Comb Spectroscopy Based on High-Harmonic Generation
• Tunable VUV Frequency Comb for ${}^{229m}$Th Nuclear Spectroscopy
• Driven electronic bridge processes via defect states in ${}^{229}$Th-doped crystals
• Optical Transmission Enhancement of Ionic Crystals via Superionic Fluoride Transfer: Growing VUV-Transparent Radioactive Crystals
• A VUV detection system for the direct photonic identification of the first excited isomeric state of ${}^{229}$Th
• Growth and characterization of thorium-doped calcium fluoride single crystals

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• Ytterbium-laser-driven THz generation in thin lithium niobate at 1.9 kW average power in a passive enhancement cavity
• Constraints on violation of Lorentz symmetry with clock-comparison redshift experiments
• Relativistic atomic structure calculations in support of spectroscopy
• Measurement of the g factor of ground-state 87Sr at the parts-per-million level using co-trapped ultracold atoms
• Coherent frequency combs from electrons colliding with a laser pulse
• Quantum Sensing Using Atomic Clocks for Nuclear and Particle Physics
• A cryogenic Paul trap for probing the nuclear isomeric excited state ${}^{229\text{m}}$Th${}^{3+}$
• Dynamically Enhanced Two-Photon Spectroscopy
• Optical clock based on two-photon spectroscopy of the nuclear transition in ion ${}^{229}$Th in a monochromatic field
• Multimessenger Astronomy Beyond the Standard Model: New Window from Quantum Sensors
• Laser fluence-dependent production of molecular thorium ions in different charge states for trapped-ion experiments
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• Characterization of non-planar ring oscillators at a wavelength of 1064 nm for high precision metrology
• Constraints on the Variation of the QCD Interaction Scale ${\Lambda }_{\text{QCD}}$
• Highly efficient nuclear population transfer through physics-informed neural networks
• Isomer depletion via nuclear excitation by inelastic electron scattering
• Broadband femtosecond lasers enable efficient two-photon excitation of the ultranarrow linewidth singlet 1s2s state in helium
• Comprehensive Assessment of ${\mathrm{Th}}^{3+}$ Properties for Nuclear Clock and Fundamental Physics Applications
• Breit corrections to moderately charged ions in all-orders calculations
• Feedforward Cancellation of High-Frequency Phase Noise in Frequency-Doubled Lasers
• Quantum Measurement Induced Radiative Processes in Continuously Monitored Optical Environments
• Probing New Forces with Nuclear Clocks