Realization of Coherent Optically Dense Media via Buffer-Gas Cooling

TL;DR

This paper demonstrates a buffer-gas cooling technique to create coherent, optically dense media with low decoherence, enabling advanced quantum optics experiments with various atoms and molecules.

Contribution

It introduces a generic buffer-gas cooling method combined with laser ablation to produce low-decoherence, high-optical-depth media suitable for coherent optical applications.

Findings

Achieved 50% transmission with OD >70 using EIT

Observed slow light with large delay-bandwidth products

Detected high-contrast spectrum oscillations due to four-wave mixing

Abstract

We demonstrate that buffer-gas cooling combined with laser ablation can be used to create coherent optical media with high optical depth and low Doppler broadening that offers metastable states with low collisional and motional decoherence. Demonstration of this generic technique opens pathways to coherent optics with a large variety of atoms and molecules. We use helium buffer gas to cool 87Rb atoms to below 7 K and slow atom diffusion to the walls. Electromagnetically induced transparency (EIT) in this medium allows for 50% transmission in a medium with initial OD >70 and for slow pulse propagation with large delay-bandwidth products. In the high-OD regime, we observe high-contrast spectrum oscillations due to efficient four-wave mixing.