Rydberg-EIT of $^{85}$Rb vapor in a cell with Ne buffer gas

TL;DR

This study explores how neon buffer gas affects Rydberg-EIT in rubidium vapor, revealing shifts and broadening of spectral lines that can be used for sensitive, non-invasive plasma diagnostics.

Contribution

It provides the first detailed experimental and theoretical analysis of buffer gas effects on Rydberg-EIT in rubidium vapor, highlighting potential applications in plasma sensing.

Findings

EIT lines exhibit a 70 MHz positive frequency shift and 120 MHz broadening at low probe power.

The line shift is primarily due to s-wave scattering and Ne atom polarization.

Results align with a model predicting linear shift dependence on buffer-gas density.

Abstract

We investigate Rydberg electromagnetically induced transparency (EIT) of $^{85}$Rb atomic vapor in a glass cell that contains a 5-Torr neon buffer gas. At low probe power, EIT lines exhibit a positive frequency shift of about 70~MHz and a broadening of about 120~MHz, with minimal dependence on the principal quantum number of the Rydberg states. The EIT line shift arises from s-wave scattering between the Rydberg electron and the Ne atoms, which induces a positive shift near 190~MHz, and from the polarization of the Ne atoms within the Rydberg atom, which adds a negative shift near -120~MHz. The line broadening is largely due to the Ne polarization. Our experimental results are in good qualitative agreement with our theoretical model, in which the shift is linear in buffer-gas density. Our results suggest that Rydberg-EIT can serve as a direct spectroscopic probe for buffer-gas density at low pressure, and that it is suitable for non-invasive measurement of electric fields in low-pressure noble-gas discharge plasmas and in dusty plasmas.