Anastassia Alexandrova

The 229Th isotope has a laser-accessible nuclear transition, not only in the gas phase, but also in 229Th doped large-band gap solids. This feature should allow a number of exciting applications: the construction of a robust and portable optical nuclear clocs; exploration of nuclear superradiance; tests of fundamental physics; and, perhaps, a new temperature standard. Solid-state 229Th nuclear clocks require a host material whose band gap is larger than the 8.4 eV nuclear transition energy. Other requirements include maximally uniform environment for every 229Th atom to avoid broadening of the transition due to dipole-dipole interactions, minimal covalency of Th with the environment to prevent the formation of intragap electronic states that can interfere with the nuclear excitation or provide undesirable decay channels via hyperfine coupling, and preferably the lack of nuclear spins in the material host. Hence, this material design task is essentially a chemical bonding task. I will present several material hosts for 229Th nuclear clocks that have been designed and tested experimentally.