  The projected systematic uncertainties of single trapped Ytterbium-ion
optical frequency standards are estimated for the quadrupole and octupole
transitions which are at wavelengths 435.5 nm and 467 nm, respectively. Finite
temperature of the ion and its interaction with the external fields introduce
drift in the measured frequency compared to its absolute value. Frequency
shifts due to electric quadrupole moment, induced polarization and excess
micromotion of the ion depend on electric fields, which are estimated in this
article. Geometry of the trap electrodes also result in unwanted electric
fields which have been considered in our calculation. Magnetic field induced
shift and Stark shifts due to electro-magnetic radiation at a surrounding
temperature are also estimated. At CSIR-NPL, we are developing a frequency
standard based on the octupole transition for which the systematic
uncertainties are an order of magnitude smaller than that using the quadrupole
transition, as described here.

Atomic Physics