Atomic absorption with ultracold atoms

V. I. Balykin

Toke Vibel, M B Christensen, M A Kristensen +4 more

Abstract The accurate determination of atom numbers is an ubiquitous problem in the field of ultracold atoms. For modest atom numbers, absolute calibration techniques are available, however, for large numbers and high densities, the available techniques neglect many-body scattering processes. Here, a spatial calibration technique for time-of-flight absorption images of ultracold atomic clouds is presented. The calibration is obtained from radially averaged absorption images and we provide a practical guide to the calibration process. It is shown that the calibration coefficient scales linearly with optical density and depends on the absorbed photon number for the experimental conditions explored here. This allows for the direct inclusion of a spatially dependent calibration in the image analysis. For typical ultracold atom clouds the spatial calibration technique leads to corrections in the detected atom number up to ≈ 12 % and temperature up to ≈ 14 % in comparison to previous calibration techniques. The technique presented here addresses a major difficulty in absorption imaging of ultracold atomic clouds and prompts further theoretical work to understand the scattering processes in ultracold dense clouds of atoms for accurate atom number calibration.

Gal Ness, Anastasiya Vainbaum, Constantine Shkedrov +2 more

We demonstrate the use of a deep-neural-network to perform absorption imaging of ultracold atoms in a single exposure. The noise in the resulting images is smaller, hence physical observables can be extracted with better accuracy.

V. I. Balykin

Renato Ejnisman

Tadas Pyragius

In this report I attempt to outline the process of developing and building an absorption imaging system capable of imaging ultracold atoms. In the theory section I will discuss the elements required to estimate the atom number and derive the equations required to determine the temperature of the atom cloud. I will outline the general features of a microscopic - two lens imaging setup via the principles of geometric optics. A discussion of optical design process and its features will be carried out with an example on absorption imaging. The essence of basic optical design process will be given.