Single-particle-sensitive imaging of freely propagating ultracold atoms

TL;DR

The paper introduces a high-dynamic-range imaging system for ultracold atoms that enables single-atom detection, high-resolution imaging of dense condensates, and potential 3D tomography, applicable to various atomic species.

Contribution

A novel imaging system that surpasses conventional absorption imaging, allowing for efficient single-atom detection and high-resolution imaging of both dilute and dense ultracold gases.

Findings

Achieved single-atom detection efficiency in dilute clouds

Imaged dense Bose-Einstein condensates without saturation

Demonstrated potential for 3D tomography with pulsed detection

Abstract

We present a novel imaging system for ultracold quantum gases in expansion. After release from a confining potential, atoms fall through a sheet of resonant excitation laser light and the emitted fluorescence photons are imaged onto an amplified CCD camera using a high numerical aperture optical system. The imaging system reaches an extraordinary dynamic range, not attainable with conventional absorption imaging. We demonstrate single-atom detection for dilute atomic clouds with high efficiency where at the same time dense Bose-Einstein condensates can be imaged without saturation or distortion. The spatial resolution can reach the sampling limit as given by the 8 \mu m pixel size in object space. Pulsed operation of the detector allows for slice images, a first step toward a 3D tomography of the measured object. The scheme can easily be implemented for any atomic species and all optical components are situated outside the vacuum system. As a first application we perform thermometry on rubidium Bose-Einstein condensates created on an atom chip.