Optical frequency standard with a single 171Yb+ ion

We report recent results on the development of an optical frequency standard based on the quadrupole transition in a single ¹⁷¹Yb⁺ ion. The probe laser frequency is simultaneously stabilised to the transmission peak of a Fabry–Perot reference cavity and the central resonance of the quadrupole transition of the ion with a linewidth of 30 Hz. With the experimentally obtained spectral characteristics of the probe laser and optical reference, a daily frequency stability on the order of 10^-17 is demonstrated for the ¹⁷¹Yb⁺ standard.