Collisional Redistribution Laser Cooling of a High Pressure Atomic Gas

TL;DR

This paper demonstrates laser cooling of a dense atomic gas through collisional redistribution of radiation, achieving cooling in a high-pressure rubidium-argon mixture with evidence from thermographic methods.

Contribution

It introduces a novel laser cooling technique applicable to high-pressure gases using collisional redistribution, expanding the scope of atomic cooling methods.

Findings

Successful cooling of rubidium gas at hundreds of bar pressure

Evidence from thermographic imaging and deflection spectroscopy

Achieved high-density cooled atomic ensemble

Abstract

We describe measurements demonstrating laser cooling of an atomic gas by means of collisional redistribution of radiation. The experiment uses rubidium atoms in the presence of several hundred bar of argon buffer gas pressure. Frequent collisions in the dense gas transiently shift a far red detuned optical field into resonance, while spontaneous emission occurs close to the unperturbed atomic transition frequency. Evidence for the cooling is obtained both via thermographic imaging and via thermographic deflection spectroscopy. The cooled gas has a density above 10$^{21}$ atoms/cm$^3$, yielding evidence for the laser cooling of a macroscopic ensemble of gas atoms.