A single strontium ion optical frequency reference for realizing accurate time

Continuously running maser and cesium beam clock ensembles form the basis for most international time scales. On week to month averaging intervals, frequency drift in these devices must be corrected in order to maintain an accurate interval for the SI second. This is typically achieved via comparison with a primary or secondary frequency standard, eg. a Cs or Rb fountain. Here we present progress towards a secondary frequency standard based on the singly-forbidden, S_{1/2} -> D_{5/2}, optical transition in a RF-trapped strontium ion. In particular, we report a novel spherical Paul trap design compatible with low systematic uncertainty, progress on miniature Sr ovens, and a titanium UHV chamber design. This clock architecture can improve upon the accuracy and stability of a microwave fountain with less complexity than quantum-logic-interrogated ion and optical lattice clocks.