Transit Ramsey EIT resonances in a Rb vacuum cell

TL;DR

This paper demonstrates a dual-channel EIT setup in a Rb vapor cell that enhances microwave frequency stabilization signals by leveraging atom transit effects and differential measurement, improving signal-to-noise ratio.

Contribution

It introduces a novel dual-channel arrangement for EIT in a vacuum Rb cell that exploits atomic transit effects to improve frequency stabilization signals.

Findings

Transient spectral features observed due to atom transit

Differential measurement enhances signal-to-noise ratio

Error signal strength comparable to single-channel methods

Abstract

We investigate a dual-channel arrangement for electromagnetically-induced transparency in a vacuum Rb vapor cell, and report the observation of a transient spectral feature due to the atoms traversing both beams while preserving their ground-state spin coherence. Despite a relatively small fraction of atoms participating in this process, their contribution to the overall lineshape is not negligible. By adjusting the path difference between the two optical beams, the differential intensity measurement can produce an error signal for the microwave frequency stabilization as strong as a single-channel measurement, but it provides a much higher signal-to-noise ratio due to the cancellation of intensity noise, dominating the signal channel detection.