Progress Toward an Optical Frequency Standard Based on a Single Indium Ion

We report on the current status of the optical frequency standard based on a single 115In+ ion. A single Indium ion is being trapped in a Paul-Strauble type trap and cooled in combination of Doppler cooling and sideband cooling to its lowest vibrational states. To interrogate the
¹
S
₀
-
³
P
₀
clock transition with high accuracy we demonstrate a Hz-level laser system resonant to this transition. With the current setup we are able to achieve a measured linewidth of the clock transition of 260 Hz. The statistical uncertainty of the absolute frequency measurement is 3×10
^-13
, limited mainly by our reference frequency standard.