${}^{229}{\mathrm{ThF}}_4$ thin films for solid-state nuclear clocks

Abstract

After nearly fifty years of searching, the vacuum ultraviolet ${}^{229}$Th nuclear isomeric transition has recently been directly laser excited [1,2] and measured with high spectroscopic precision [3]. Nuclear clocks based on this transition are expected to be more robust [4,5] than and may outperform [6,7] current optical atomic clocks. They also promise sensitive tests for new physics beyond the standard model [5,8,9]. In light of these important advances and applications, a dramatic increase in the need for ${}^{229}$Th spectroscopy targets in a variety of platforms is anticipated. However, the growth and handling of high-concentration ${}^{229}$Th-doped crystals [5] used in previous measurements [1-3,10] are challenging due to the scarcity and radioactivity of the ${}^{229}$Th material. Here, we demonstrate a potentially scalable solution to these problems by demonstrating laser excitation of the nuclear transition in ${}^{229}$ThF${}_4$ thin films grown with a physical vapor deposition process, consuming only micrograms of ${}^{229}$Th material. The ${}^{229}$ThF${}_4$ thin films are intrinsically compatible with photonics platforms and nanofabrication tools for integration with laser sources and detectors, paving the way for an integrated and field-deployable solid-state nuclear clock with radioactivity up to three orders of magnitude smaller than typical \thor-doped crystals [1-3,10]. The high nuclear emitter density in ${}^{229}$ThF${}_4$ also potentially enables quantum optics studies in a new regime. Finally, we describe the operation and present the estimation of the performance of a nuclear clock based on a defect-free ThF${}_4$ crystal.

15 pages, 3 figures

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Cited by in corpus (11)

• Theory of internal conversion of the thorium-229 nuclear isomer in solid-state hosts
• ${}^{229}$Th Nuclear Spectroscopy in an Opaque Material: Laser-Based Conversion Electron Mössbauer Spectroscopy of ${}^{229}$ThO${}_2$
• Continuous-wave laser source at the 148 nm nuclear transition of Th-229
• Prediction of Nuclear Clock Transitions Frequency Difference between ${}^{229}$Th${}^{3+}$ and ${}^{229}$Th${}^{4+}$ via \textit{ab-initio} Self-Consistent Field Theory
• A continuous-wave vacuum ultraviolet laser for the nuclear clock
• A cryogenic Paul trap for probing the nuclear isomeric excited state ${}^{229\text{m}}$Th${}^{3+}$
• Quantum Sensing Using Atomic Clocks for Nuclear and Particle Physics
• Optical clock based on two-photon spectroscopy of the nuclear transition in ion ${}^{229}$Th in a monochromatic field
• Constraints on the Variation of the QCD Interaction Scale ${\Lambda }_{\text{QCD}}$
• Probing New Forces with Nuclear Clocks
• Scalable Dark Matter Searches Using Integrated Photonics