Driven Electronic Bridge Processes Via Defect States in Th229 -Doped Crystals

Brenden S. Nickerson, ∗ Martin Pimon, Pavlo V. Bilous, 1 Johannes Gugler, Georgy A. Kazakov, Tomas Sikorsky, Kjeld Beeks, Andreas Grüneis, 2 Thorsten Schumm, and Adriana Pálffy 1, † Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany Center for Computational Material Science, Technische Universität Wien, 1040 Vienna, Austria Max-Planck-Institut für die Physik des Lichts, D-91058 Erlangen, Germany Atominstitut, Technische Universität Wien, 1020 Vienna, Austria Institute for Theoretical Physics, Technische Universität Wien, 1040 Vienna, Austria Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany (Dated: Monday 22 March, 2021) The electronic defect states resulting from doping Th in CaF2 offer a unique opportunity to excite the nuclear isomeric state Th at approximately 8 eV via electronic bridge mechanisms. We consider bridge schemes involving stimulated emission and absorption using an optical laser. The role of different multipole contributions, both for the emitted or absorbed photon and nuclear transition, to the total bridge rates are investigated theoretically. We show that the electric dipole component is dominant for the electronic bridge photon. In contradistinction, the electric quadrupole channel of the Th isomeric transition plays the dominant role for the bridge processes presented. The driven bridge rates are discussed in the context of background signals in the crystal environment and of implementation methods. We show that inverse electronic bridge processes quenching the isomeric state population can improve the performance of a solid-state nuclear clock based on Th.