Industrial 171Yb+ single-ion optical clock with systematic uncertainty below 2×10^−17

We present the setup of our optical frequency standard (OFS) “TOPTICLOCK”. It is based on the 2S1/2 (F=0) – 2D3/2 (F=2) electric quadrupole transition at 435.5 nm of a single laser-cooled and trapped 171Yb+ ion. All required subsystems are contained in two transportable 19” rack compartments. By comparing it with a laboratory-style OFS of the German National Metrology Institute (PTB), which operates on the 467 nm electric octupole transition, using a TOPTICA DFC optical frequency comb, a frequency instability of 5×10-15/√τ with systematic uncertainty below 2×10-17 was demonstrated. The performance of TOPTICLOCK was also benchmarked by directly comparing it to another OFS operating also at the 435.5 nm clock transition. An agreement between both systems with a total uncertainty well below 10-17 was obtained.