Doppler-free Rydberg Spectroscopy in Warm Vapor

TL;DR

This paper demonstrates a three-laser Doppler-free excitation method in warm vapor that significantly enhances Rydberg atom density and narrows spectral lines, improving the efficiency of Rydberg-based technologies.

Contribution

It introduces a novel three-laser Doppler-free excitation scheme with k-vectors summing to zero, leading to improved Rydberg excitation efficiency and spectral resolution.

Findings

Three-times increase in Rydberg density

Near four-times reduction in spectral line-widths

Enhanced potential for Rydberg-based sensing and photon sources

Abstract

The common approach for producing Rydberg atoms in warm vapor cells is with lasers arranged in a counter-propagating, collinear configuration. Doppler effects in these configurations reduce the efficiency of excitation to the Rydberg state while also producing broadened spectral features. In this work, we demonstrate a three-laser Doppler-free excitation using laser beams whose k-vectors sum to zero, resulting in an enhancement in the Rydberg density and narrowed spectral features. A three-times enhancement to Rydberg density along with a near four-times reduction in spectroscopic line-widths are observed compared to a collinear configuration. This Doppler-free configuration could prove beneficial to Rydberg atomic technologies, such as electric field sensing with small volumes or deterministic photon sources.