Trapping and cooling of rf-dressed atoms in a quadrupole magnetic field

TL;DR

This paper investigates the spontaneous evaporation of atoms in an rf-dressed quadrupole magnetic trap, revealing how holes in the trap influence evaporation and temperature, with modeling showing limited phase space density increase.

Contribution

It demonstrates the role of rf coupling holes in atom evaporation in a quadrupole trap and models the process with Monte-Carlo simulations, providing insights into trap dynamics.

Findings

Evaporation occurs at holes where rf coupling vanishes.

Temperature is determined by a balance between heating and evaporation.

Monte-Carlo simulation predicts limited phase space density increase.

Abstract

We observe the spontaneous evaporation of atoms confined in a bubble-like rf-dressed trap (Zobay and Garraway, 2001). The atoms are confined in a quadrupole magnetic trap and are dressed by a linearly polarized rf field. The evaporation is related to the presence of holes in the trap, at the positions where the rf coupling vanishes, due to its vectorial character. The final temperature results from a competition between residual heating and evaporation efficiency, which is controlled via the height of the holes with respect to the bottom of the trap. The experimental data are modeled by a Monte-Carlo simulation predicting a small increase in phase space density limited by the heating rate. This increase was within the phase space density determination uncertainty of the experiment.