Laser Cooling of Dense Rubidium-Noble Gas Mixtures via Collisional Redistribution of Radiation

TL;DR

This paper reports on laser cooling of dense rubidium-noble gas mixtures using collisional redistribution of radiation, demonstrating the technique's effectiveness in cooling macroscopic gas samples with different buffer gases.

Contribution

It introduces a method for laser cooling dense alkali-noble gas mixtures through collisional redistribution, enabling cooling of large gas ensembles.

Findings

Helium buffer gas results in smaller temperature changes.

Argon buffer gas improves heat transfer within the cell.

The technique effectively cools macroscopic gas samples.

Abstract

We describe experiments on the laser cooling of both helium-rubidium and argon-rubidium gas mixtures by collisional redistribution of radiation. Frequent alkali-noble gas collisions in the ultradense gas, with typically 200\,bar of noble buffer gas pressure, shift a highly red detuned optical beam into resonance with a rubidium D-line transition, while spontaneous decay occurs close to the unshifted atomic resonance frequency. The technique allows for the laser cooling of macroscopic ensembles of gas atoms. The use of helium as a buffer gas leads to smaller temperature changes within the gas volume due to the high thermal conductivity of this buffer gas, as compared to the heavier argon noble gas, while the heat transfer within the cell is improved.