Autler-Townes splitting of a cascade system in ultracold cesium Rydberg atoms

Abstract

Autler-Townes (AT) splitting is observed in ultracold cesium Rydberg gases. Frequency and power of the laser field coupling $6S$${}_{1/2}$ and $6P$${}_{3/2}$ levels are tuned to influence the population redistribution of $6P$${}_{3/2}$ and $nS$ levels excited by another light. The profile of AT spectroscopy is measured experimentally and compared with the theoretical simulation considering the estimated large dephasing rates caused by interaction between Rydberg atoms, which demonstrates that splitting and profile of AT spectra are strongly dependent on the interaction between Rydberg atoms. Rabi frequency of the coupling laser and transition dipole moment of $6S$${}_{1/2}\ensuremath{\rightarrow}$ $6P$${}_{3/2}$ are deduced via fitting the measured space variation of two splitting peaks, which is consistent with theoretical calculations.