The first frequency- and time-domain observations of the resonant large cavity and multiatom vacuum Rabi splitting are reported. The transmission as a function of frequency (time) of a weak CW (pulsed) laser beam through a high-finesse (500), 1-cm, 7.5-GHz, free-spectral-range, confocal Fabry-Perot cavity containing 850-1400 barium atoms has been measured. A plot of cavity intensity throughput as a function of the frequency of the CW input beam is shown and discussed. The spectrum, which represents the transmission function of the cavity, provides a way to calculate the transient response of the atom-cavity transmission based on linear systems theory. Equivalently, the same transient response of the transmission is predicted in terms of the quantized atom-cavity interaction. In either case, a damped oscillatory response is expected. To study this case, the temporal profile of a weak, smooth, ≅8-ns pulse after transmission through the cavity in a case where the number of Ba atoms within the cavity resulted in a large frequency-domain splitting was recorded. Excellent agreement with linear systems theory is observed.
