Toward nanophotonic platforms for solid-state $^{229}$Th nuclear clocks
Abstract
While the Th nuclear isomer has recently been observed and laser-excited, converting optical nuclear manipulation into a chip-scale solid-state frequency standard remains an open challenge. Here, we present a nanophotonic platform to realize an all-solid-state nuclear clock based on the low-energy isomeric transition of Th embedded in high- fluoride photonic resonators. By coupling ensembles of thorium nuclei to confined optical modes, we show that resonant field build-up in the cavity can substantially enhance the nuclear excitation rate, enabling optical interrogation at practical laser intensities. We model the nuclei-photon interaction dynamics and outline a technological roadmap toward addressing this challenge, including resonator fabrication in fluoride crystals, thorium implantation, nuclear excitation with integrated lasers, and on-chip detection of vacuum-ultraviolet photons. As an initial proof of concept, we implant a crystalline fluoride whispering-gallery-mode resonator with Th and assess the impact of implantation-induced damage on resonator performance. Our platform leverages recent advances in materials integration and nanophotonics to chart a realistic route toward compact and scalable nuclear frequency standards.
Cite
@article{arxiv.2604.20687,
title = {Toward nanophotonic platforms for solid-state $^{229}$Th nuclear clocks},
author = {Sandro Kraemer and Karen Mamian and Toby Bi and Shun Fujii and Jan de Haan and Harshith Babu and Arno Claessens and Rafael Ferrer Garcia and Fedor Ivandikov and Piet Van Duppen and Andreas Dragoun and Christoph E. Düllmann and Christoph Marquardt and Ulrich Wahl and Bart Kuyken and Thorsten Schumm and Pascal Del'Haye and Lino M. C. Pereira and Georgy A. Kazakov and Kasper Van Gasse and Charles Roques-Carmes},
journal= {arXiv preprint arXiv:2604.20687},
year = {2026}
}