Description du projet
La première horloge nucléaire au thorium fait son chemin
Le projet ThoriumNuclearClock, financé par l’UE, révolutionnera le développement de la première horloge nucléaire, basée sur une transition énergétique dans le noyau du thorium-229, un des isotopes du thorium. Cette avancée promet de surpasser d’un ordre de grandeur la précision des meilleures horloges atomiques actuelles (qui utilisent des changements dans les niveaux d’énergie des électrons de l’enveloppe de l’atome). Le projet développera trois horloges prototypes nucléaires au thorium en appliquant des approches complémentaires à des ions piégés et des solides, ainsi que des lasers ultraviolets sous vide afin d’exciter l’isotope de thorium. Comparer ces horloges entre elles et avec des horloges optiques de pointe permettra d’évaluer la nouvelle norme de fréquence avant de l’appliquer pour tester la physique fondamentale.
Objectif
Th-229 has an exceptionally low-energy excited nuclear isomer state with an excitation energy of only a few electron volts, making it accessible to laser manipulation. With a predicted relative radiative linewidth of 1e-19, constructing a Thorium nuclear clock becomes possible that could rival todays most advanced optical atomic clocks.
The few-eV transition emerges from a fortunate near-degeneracy of the two lowest nuclear energy levels. However, the Coulomb and strong-force contributions to these level energies differ on the MeV level. This makes the Th-229 nuclear level structure uniquely sensitive to variations of fundamental constants and ultralight dark matter.
Very recently, the applicants have proven the long-sought existence of the low-energy isomer, determined the lifetime in different electronic environments, quantified the nuclear moments and charge radius based on the hyperfine splitting, and constrained the isomer energy. However, knowledge on the electronic and nuclear properties is still insufficient to exploit the Th-229 system for fundamental tests.
This project aims to close this gap and realize three prototype nuclear Thorium clocks using complementary approaches in trapped ions and solids. We will develop customized VUV laser systems and perform precision spectroscopy of the Th-229 nuclear transition. Comparing these clocks among each other and with state-of-the-art optical clocks will allow us to benchmark the new frequency standard before ultimately applying it to test fundamental physics.
This project requires a unique combination of experimental and theoretical expertise in atomic and nuclear physics, high precision metrology and fundamental symmetries. Furthermore, special infrastructure is required for (distributed) clock comparison, precision spectroscopy as well as processing of Th-229. The synergy team is composed to optimally respond to these challenges while being rooted in established and successful collaborations.
Champ scientifique
Programme(s)
Thème(s)
Régime de financement
ERC-SyG - Synergy grantInstitution d’accueil
1040 Wien
Autriche