Direct observation of atomic diffusion in warm rubidium ensembles

TL;DR

This paper introduces a robust optical method to measure atomic diffusion coefficients in warm rubidium ensembles with various buffer gases, providing precise values for different gases at standard conditions.

Contribution

The paper presents a novel optical pumping and imaging technique to accurately determine atomic diffusion coefficients in warm rubidium with multiple buffer gases.

Findings

Measured diffusion coefficients for rubidium in neon, krypton, and xenon.

Demonstrated a reliable optical method for diffusion measurement.

Provided data at standard temperature and pressure.

Abstract

We present a robust method for measuring the diffusion coefficients of warm atoms in buffer gases. Using optical pumping, we manipulate the atomic spin in a thin cylinder inside the cell. Then we observe the spatial spread of optically pumped atoms in time using a camera, which allows us to determine the diffusion coefficient. As an example, we demonstrate measurements of diffusion coefficients of rubidium in neon, krypton and xenon acting as buffer gases. We have determined the normalized (273 K, 760 Torr) diffusion coefficients to be 0.18$\pm$0.03 cm$^2$/s for neon, 0.07$\pm$0.01 cm$^2$/s for krypton, and 0.052$\pm$0.006 cm$^2$/s for xenon.