Rydberg Raman Ramsey EIT

Rydberg states of atoms are of interest due to their high electric susceptibility and potential applications for electric field sensors. A common optical detection of Rydberg atoms uses a two photon Electromagnetically induced transparency (EIT) transmission peak as a frequency marker and is achieved by two counter-propagating optical fields at 780 nm and 480 nm. Its sensitivity for atomic vapor is limited by the residual Doppler broadening. Here we theoretically investigate a possibility to boost the sensor response by reducing the resonance width using a temporal and potentially spatial Ramsey interrogation. Two spatially separated EIT channels create a Ramsey sequence where atomic Rydberg coherence is prepared in the first region, evolves with no applied optical fields in a “dark region” between the two channels, and then is probed in the second channel. We show that the linewidth of such a Raman-Ramsey fringe can be theoretically reduced to 50 kHz with room temperature Rydberg atoms. This theoretical work suggests an approach to have a narrow EIT feature with reduced power broadening which could be potentially beneficial for increased sensitivity in EIT-based Rydberg electrometers. Preliminary experimental verification of this theory is in progress.