An optical frequency standard based on the 2S1/2—2F7/2 transition in 171Yb+

The
²
S
^1/2
(F = 0) -
²
F
_7/2
(F = 3, m
_F
= 0) transition at 467 nm in a single, trapped, laser cooled ion of
¹⁷¹
Yb
⁺
has the potential to be an extremely accurate optical frequency reference. Systematic shifts have been evaluated and are currently dominated by the ac-Stark shift. However, this is not expected to be the case as probe laser linewidth is reduced. A heterodyne measurement of the probe laser shows it to have a width of 20 Hz on a 1 minute timescale. The atomic spectrum on the other hand, has been found to have a broadened width of 200 Hz. Using heterodyne detection of light reflected from the trap electrodes, Doppler shifting due to vibration of the trap is identified as the additional source of broadening.