In-trap fluorescence detection of atoms in a microscopic dipole trap

Abstract

We investigate fluorescence detection using a standing wave of blue-detuned light of one or more atoms held in a deep, microscopic dipole trap. The blue-detuned standing wave realizes a Sisyphus laser cooling mechanism so that an atom can scatter many photons while remaining trapped. When imaging more than one atom, the blue detuning limits loss due to inelastic light-assisted collisions. Using this standing-wave probe beam, we demonstrate that we can count from 1 to the order of 100 atoms in the microtrap with sub-Poissonian precision.