Counting atoms in a deep optical microtrap

Opt Lett. 2011 Apr 1;36(7):1041-3. doi: 10.1364/OL.36.001041.

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 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.