In Situ Measurements of Light Diffusion in an Optically Dense Atomic Ensemble

Area of Science:

• Atomic physics
• Quantum optics
• Condensed matter physics

Background:

• Understanding light transport in complex media is crucial for various scientific fields.
• Optically thick atomic ensembles present unique challenges for studying light propagation due to multiple scattering events.

Purpose of the Study:

• To introduce a novel method for investigating in-situ light transport in optically thick cold atom ensembles.
• To observe and characterize the diffusive regime of light propagation within these systems.

Main Methods:

• Utilizing the internal structure of alkaline-earth metals for optical excitation.
• Creating an optical excitation at the center of a large atomic cloud.
• Observing light propagation through multiple scattering events.

Main Results:

• Demonstrated a method for controlled optical excitation within atomic clouds.
• Identified a diffusive regime when the cloud size exceeds the transport mean free path.
• Measured key diffusion parameters (diffusion coefficient, transport velocity, transport time) showing agreement with diffusion models.

Conclusions:

• The developed method allows for direct, time- and space-resolved observation of light diffusion in atomic ensembles.
• This approach provides a promising platform for exploring novel diffusion regimes in quantum systems.