TY - JOUR AU - Chuankun Zhang AU - Lars von der Wense AU - Jack Doyle AU - Jacob Higgins AU - Tian Ooi AU - Hans Friebel AU - Jun Ye AU - R. Elwell AU - J. Terhune AU - H. Morgan AU - A. Alexandrova AU - H. Tan AU - Andrei Derevianko AU - Eric Hudson AB -

After nearly fifty years of searching, the vacuum ultraviolet 229Th 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 229Th spectroscopy targets in a variety of platforms is anticipated. However, the growth and handling of high-concentration 229Th-doped crystals [5] used in previous measurements [1-3,10] are challenging due to the scarcity and radioactivity of the 229Th material. Here, we demonstrate a potentially scalable solution to these problems by demonstrating laser excitation of the nuclear transition in 229ThF4 thin films grown with a physical vapor deposition process, consuming only micrograms of 229Th material. The 229ThF4 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 229ThF4 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 ThF4 crystal.

BT - Nature DA - 2024-12-1 N2 -

After nearly fifty years of searching, the vacuum ultraviolet 229Th 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 229Th spectroscopy targets in a variety of platforms is anticipated. However, the growth and handling of high-concentration 229Th-doped crystals [5] used in previous measurements [1-3,10] are challenging due to the scarcity and radioactivity of the 229Th material. Here, we demonstrate a potentially scalable solution to these problems by demonstrating laser excitation of the nuclear transition in 229ThF4 thin films grown with a physical vapor deposition process, consuming only micrograms of 229Th material. The 229ThF4 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 229ThF4 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 ThF4 crystal.

PY - 2024 T2 - Nature TI - ^{229}ThF_4 thin films for solid-state nuclear clocks UR - https://arxiv.org/abs/2410.01753 VL - in press ER -