Summary:
Researchers in the Department of Physics and Astronomy at UCLA have developed a novel technique to harness thorium-229 using nonlinear optical crystals and fibers to generate necessary wavelengths in a vacuum-free and defect-resistant system.
Background:
Isomeric nuclear transition is a phenomenon that occurs when atoms transition from an excited state to a lower energy state, generating useful energy stored in nuclear bonds. The thorium-229 isomeric nuclear transition holds significant potential for advanced technologies, including ultra-precise nuclear clocks and sensors for electromagnetic fields, gravitational forces, and chemical interactions. These innovations could revolutionize timekeeping, navigation, and fundamental physics research by enhancing accuracy and sensitivity. However, a primary challenge in utilizing this transition is its requirement for 148nm light, which falls within the vacuum ultraviolet (VUV) range. Light at this wavelength cannot propagate in air, thus some apparatus components must be held in vacuum which increases design complexity and operational costs. Additionally, thorium doping often introduces electronic defects and is susceptible to detrimental magnetic field effects. To facilitate the practical implementation of thorium-229 transitions, it is essential to engineer a system that operates in non-vacuum environments while mitigating magnetic field interference.
Innovation:
UCLA researchers in the Department of Physics and Astronomy have developed a novel configuration using nonlinear optical crystals or fibers to generate shorter-wavelength (higher frequency) light from longer-wavelength (lower frequency) incident light. A key innovation of this technique is the use of a nonlinear optical crystal or fiber doped with thorium-229, enabling light sources outside the VUV spectrum to generate the precise 148 nm wavelength required to induce nuclear transitions within the crystal or fiber. Because both the thorium-229 and the generated light remain within the crystal or fiber, there is no need for a vacuum environment, simplifying operation and reducing system complexity. Further, the research team has engineered materials with optimized electron configuration and spin properties, ensuring defect-free thorium doping without magnetic field effects. This advancement is crucial for bringing nuclear clock technology and next-generation sensing devices closer to real-world applications, facilitating their integration into a variety of scientific, industrial, and defense technologies.
Potential Applications:
● Nuclear clocks
● High precision sensors, including electromagnetic field detection, gravitational sensing, and chemical/biological sensors
● Quantum computing and quantum information
● Physics research
● Advanced metrology
● Radiation detection, thermal management, and nuclear fuel systems
● Advanced spectroscopy and integrated photonics
Advantages:
● Elimination of vacuum requirement
● Enhanced stability and precision
● Compact, scalable design
● Broad wavelength compatibility
● Lower operational costs
● Defect-free thorium-doped crystals
State of Development:
The inventors have developed the an initial conception of the invention as of October 2024.
Reference:
UCLA Case No. 2024-241 & UCLA Case No. 2025-172
Relevant Publications:
1. Description of the crystal based nuclear clock: Wade G. Rellergert, D. DeMille, R. R. Greco, M. P. Hehlen, J. R. Torgerson, and Eric R. Hudson Phys. Rev. Lett. 104, 200802 – Published 20 May 2010
2. Laser Excitation of the 229Th nuclear isomeric transition in a solid-state host R. Elwell, Chrisian Schneider, Justin Jeet, J.E.S. Terhune, H.W.T. Morgan, A.N. Alexandrova, H.B. Tran Tan, Andrei Derevianko, and Eric R. Hudson arXiv:2404.12311 (2024)
3. Laser Excitation of the Th-229 Nucleus J. Tiedau, M. V. Okhapkin, K. Zhang, J. Thielking, G. Zitzer, E. Peik, F. Schaden, T. Pronebner, I. Morawetz, L. Toscani De Col, F. Schneider, A. Leitner, M. Pressler, G. A. Kazakov, K. Beeks, T. Sikorsky, and T. Schumm Phys. Rev. Lett. 132, 182501 – Published 29 April 2024
4. Zhang, C., Ooi, T., Higgins, J.S. et al. Frequency ratio of the 229mTh nuclear isomeric transition and the 87Sr atomic clock. Nature 633, 63–70 (2024). https://doi.org/10.1038/s41586-024-07839-
5. 229ThF4 thin films for solid-state nuclear clocks Chuankun Zhang, Lars von der Wense, Jack F. Doyle, Jacob S. Higgins, Tian Ooi1, Hans U. Friebel, Jun Ye, R. Elwell, J.E. S. Terhune, H. W. T. Morgan, A. N. Alexandrova, H. B. Tran Tan, Andrei Derevianko, and Eric R. Hudson Nature 636, 603 (2024) – Published 18 December 2024
6. Theory of internal conversion of the thorium-229 nuclear isomer in solid-state hosts H. W. T. Morgan, H. B. Tran Tan, R. Elwell, A. N.Alexandrova, Eric R. Hudson, Andrei Derevianko, arXiv:2411.15641 (2024)
Lead Inventor:
Eric R. Hudson, UCLA Professor in the Department of Physics and Astronomy