Optical pumping effects on the Rydberg EIT spectrum

TL;DR

This paper investigates how optical pumping influences Rydberg EIT spectra in thermal rubidium vapor, demonstrating controllable enhancement or suppression of EIT signals and providing a quantitative theoretical model.

Contribution

It offers a universal analysis of optical pumping effects on Rydberg EIT, combining experimental measurements with a Doppler-free numerical model to clarify underlying mechanisms.

Findings

EIT peak height can be doubled or reduced by an order of magnitude.

Linewidth is slightly narrowed by optical pumping.

EIT enhancement depends on probe intensity and optical density.

Abstract

We provide a universal discussion of the interplay between Rydberg-state electromagnetically induced transparency (EIT) and optical pumping (OP) in a thermal Rb87 medium. By pumping the population to one single Hyperfine/Zeeman state, we can enhance the interaction strength and, in principle, amplify the EIT peak. According to our measurements, the EIT peak height can be improved by a factor of two or reduced by one order of magnitude, and linewidth was slightly narrowed by the pumping effect. Similar behavior is also seen by increasing the optical density (OD) of the medium. The EIT feature is predicted quantitatively using a Doppler-free non-perturbation numerical calculation. With and without the optical pumping field, the EIT peak heights collapse onto the same theoretical curve, showing that OP and varying OD have the same effect. In both simulations and measurements, Rydberg EIT enhancement through OP is dependent on the intensity of the probe field and the OD. Our work clarifies the underlying mechanisms of optical pumping and advances Rydberg-atom research.