Counting atoms in a deep optical microtrap

TL;DR

This paper presents a method for accurately counting small numbers of atoms in a deep optical microtrap by fluorescence collection, utilizing a blue-detuned standing wave that enables cooling and minimizes atom loss.

Contribution

The authors introduce a novel fluorescence-based counting technique that employs blue detuning and Sisyphus cooling to improve atom counting accuracy in microscopic traps.

Findings

Effective counting of multiple atoms in a microtrap

Reduced atom loss due to light-assisted collisions

Successful implementation of fluorescence detection with cooling

Abstract

We demonstrate a method to count small numbers of atoms held in a deep, microscopic optical dipole trap by collecting fluorescence from atoms exposed to a standing wave of light that is blue detuned from resonance. While scattering photons, the atoms are also cooled by a Sisyphus mechanism that results from the spatial variation in light intensity. The use of a small blue detuning limits the losses due to light assisted collisions, thereby making the method suitable for counting several atoms in a microscopic volume.