Optimizing the Rydberg EIT spectrum in a thermal vapor

TL;DR

This paper investigates how laser polarization, magnetic fields, laser intensities, and optical density affect Rydberg-EIT spectra in thermal rubidium vapor, providing a model for optimizing high-contrast quantum sensing signals.

Contribution

It offers a comprehensive analysis and a quantitative model for optimizing Rydberg-EIT spectra in thermal vapor, enhancing quantum sensor performance.

Findings

Achieved Rydberg EIT peak contrast of 13%, over twice the room temperature maximum.

Developed an analytic transmission model fitting spectra under various conditions.

Optimized Rydberg EIT contrast using laser intensity and optical density adjustments.

Abstract

We present Rydberg-state electromagnetically-induced-transparency (EIT) measurements examining the effects of laser polarization, magnetic fields, laser intensities, and the optical density of the thermal $^{87}$Rb medium. Two counter-propagating laser beams with wavelengths of 480 nm and 780 nm were employed to sweep the spectrum across the Rydberg states $|33D_{3/2}\rangle$ and $|33D_{5/2}\rangle$. An analytic transmission expression well fits the Rydberg-EIT spectra with multiple transitions under different magnetic fields and laser polarization after accounting for the relevant Clebsch-Gordan coefficients, Zeeman splittings, and Doppler shifts. In addition, the high-contrast Rydberg EIT can be optimized with the probe laser intensity and optical density. Rydberg EIT peak height was achieved at $13\%$, which is more than twice as high as the maximum peak height at room temperature. A quantitative theoretical model is employed to represent the spectra properties and to predict well the optimization conditions. A Rydberg EIT spectrum with high contrast in real-time can be served as a quantum sensor to detect the electromagnetic field within an environment.