Two different atomic oscillators in the same environment: a new technique for compensating perturbations

Presents a new technique for compensating frequency drift in a trapped ion frequency standard by simultaneously holding /sup 171/Yb/sup +/ and /sup 199/Hg/sup +/. Environmental perturbations affect the hyperfine splitting of these two ions very differently. By monitoring the changes in the frequency difference between their hyperfine levels we can compensate for some of the frequency drift due to changes in external perturbations.