Table 1 Summary of the systematic frequency shifts.

From: Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms

Effects

Shifts at 778 nm

Light shift

−43.2 ± 3 kHz

Relativistic shift

−360 ± 1 Hz

Collisions shift

−181 ± 16 Hz

Collisions shift due to background gases

<1 kHz

Black-body radiation shift

−330 ± 4 Hz

Magnetic shift

<703 Hz

Electronic shifts

−1.6 ± 0.2 kHz