Progress in the evaluation and operation of the NRC strontium single ion frequency standard as an optical atomic clock

Improved functionality and accuracy of the NRC Sr+ single trapped ion 445-THz standard is described. Absolute frequency stabilization of all laser sources has been achieved together with loading of the ion trap using photo-ionization methods. An Erbium fiber laser based frequency comb is used to directly measure the 445-THz clock frequency. A 9 hr preliminary measurement was performed with statistical uncertainty of 1.4 Hz (3×10−15) in excellent agreement with a previously reported value in 2005. A new endcap trap with probing and micromotion correction in three dimensions has been assembled and will have uncertainties approaching 10−17 in the near future.