Probing an excited-state atomic transition using hyperfine quantum beat spectroscopy

TL;DR

This paper introduces a method using hyperfine quantum beat spectroscopy to observe and analyze excited-state atomic transitions in cesium vapor at room temperature, revealing Autler-Townes splitting and Rabi oscillations.

Contribution

It demonstrates a novel application of quantum beat spectroscopy to probe excited-state dynamics and provides a detailed model that matches experimental observations.

Findings

Observation of quantum beats modified by excited-state transition driving

Detection of Autler-Townes splitting in hyperfine levels

Evidence of Rabi oscillations on the excited-state transition

Abstract

We describe a method to observe the dynamics of an excited-state transition in a room temperature atomic vapor using hyperfine quantum beats. Our experiment using cesium atoms consists of a pulsed excitation of the D2 transition, and continuous-wave driving of an excited-state transition from the 6P$_{3/2}$ state to the 7S$_{1/2}$ state. We observe quantum beats in the fluorescence from the 6P$_{3/2}$ state which are modified by the driving of the excited-state transition. The Fourier spectrum of the beat signal yields evidence of Autler-Townes splitting of the 6P$_{3/2}$, F = 5 hyperfine level and Rabi oscillations on the excited-state transition. A detailed model provides qualitative agreement with the data, giving insight to the physical processes involved.