Reducing the EIT resonance width using Rydberg Raman-Ramsey (R³)

Two-photon optical resonances such as electromagnetically induced transparency (EIT) involving highly excited Rydberg atomic states have attracted attention thanks to their potential application for sensitive detection of AC and DC electric fields. When vapor cells are used, however, the sensitivity is limited by the residual Doppler effect and optical power broadening. We theoretically explore the possibility to reduce the EIT spectral linewidth by utilizing a Ramsey approach, allowing multiple interrogations of atomic coherence. We developed a model to perform a temporally or spatially separated interrogation, and calculations predict the linewidth of such a Raman-Ramsey spectral feature is substantially reduced compared to standard Doppler-broadened EIT. We also discuss some preliminary experimental efforts to observe these narrow spectral features in both the temporally and spatially separated approaches along with associated technical challenges.