Two-photon Doppler-free spectroscopy of the 6s squared; 1S 0 to 6s23s; 1S 0 Rydberg transition for quantum sensing in ytterbium
Researchers used two-photon Doppler-free spectroscopy to study a transition in Ytterbium (Yb) from a ground state ($6s^2~^1S_0$) to a Rydberg state ($6s23s~^1S_0$). They found this transition is highly favorable for sensing because it is immune to first-order Zeeman shifts and has low sensitivity to density changes. Theoretical calculations provided properties like the $C_6$ coefficient, suggesting potential use in quantum clocks or thermometers.