Evaporation limited loading of an atom trap

TL;DR

This paper models the dynamics of atom loading in an optical dipole trap with a unique geometry, highlighting evaporation processes and proposing methods to improve atom retention and cooling efficiency.

Contribution

It introduces a rate equation model for the loading process considering non-uniform trap potentials and two-dimensional evaporation, advancing understanding of atom trap dynamics.

Findings

Collision statistics reveal dominant loss processes.

Model matches experimental data, guiding trap optimization.

Independent control of confinement speeds up evaporative cooling.

Abstract

Recently, we have experimentally demonstrated a continuous loading mechanism for an optical dipole trap from a guided atomic beam [1]. The observed evolution of the number of atoms and temperature in the trap are consequences of the unusual trap geometry. In the present paper, we develop a model based on a set of rate equations to describe the loading dynamics of such a mechanism. We consider the collision statistics in the non-uniform trap potential that leads to twodimensional evaporation. The comparison between the resulting computations and experimental data allows to identify the dominant loss process and suggests ways to enhance the achievable steady-state atom number. Concerning subsequent evaporative cooling, we find that the possibility of controlling axial and radial confinement independently allows faster evaporation ramps compared to single beam optical dipole traps.