Atomic optical clocks and search for variation of the fine-structure constant - art. no. 034502

Theories unifying gravity and other interactions suggest the possibility of spatial and temporal variations of physical "constants." Accuracy achieved for atomic optical frequency standards (optical clocks) approaches the lev el when possible time evolution of the fine-structure constant ct can be st udied by comparisons of rates between clocks based on different atomic tran sitions in different atoms. The sensitivity to variation of alpha is due to relativistic corrections that are different in different atoms (similar to Z(2)alpha(2)). We have calculated the values of the relativistic energy sh ifts in In II, Tl II, Ba II, and Ra II, which all can be used as atomic opt ical clocks. The results are to be used to translate any change in the cloc k's rate into variation of alpha.