Single-Ion Nuclear Clock for Metrology at the 19th Decimal Place

The 7.6(5) eV nuclear magnetic-dipole transition in a single Th-229(3+) ion may provide the foundation for an optical clock of superb accuracy. A virtual clock transition composed of stretched states within the 5F(5/2) electronic ground level of both nuclear ground and isomeric manifolds is proposed. It is shown to offer unprecedented systematic shift suppression, allowing for clock performance with a total fractional inaccuracy approaching 1 x 10(-19).