Detection of slow atoms confined in a Cesium vapor cell by spatially separated pump and probe laser beams

TL;DR

This paper presents a method to detect and count slow atoms near a surface in a Cesium vapor cell using spatially separated pump and probe beams, advancing spectroscopic techniques with potential sub-Doppler resolution.

Contribution

It introduces a novel approach employing spatially separated laser beams to observe and quantify slow atoms, addressing limitations of traditional velocity distribution assumptions.

Findings

Successful detection of slow atoms using the proposed method

Experimental progress toward counting slow atoms near surfaces

Potential for improved spectroscopic resolution

Abstract

The velocity distribution of atoms in a thermal gas is usually described through a Maxwell-Boltzman distribution of energy, and assumes isotropy. As a consequence, the probability for an atom to leave the surface under an azimuth angle {\theta} should evolve as cos {\theta}, in spite of the fact that there is no microscopic basis to justify such a law. The contribution of atoms moving at a grazing incidence towards or from the surface, i.e. atoms with a small normal velocity, here called "slow" atoms, reveals essential in the development of spectroscopic methods probing a dilute atomic vapor in the vicinity of a surface, enabling a sub-Doppler resolution under a normal incidence irradiation. The probability for such "slow" atoms may be reduced by surface roughness and atom-surface interaction. Here, we describe a method to observe and to count these slow atoms relying on a mechanical discrimination, through spatially separated pump and probe beams. We also report on our experimental progresses toward such a goal.