Production of a chromium Bose-Einstein condensate

TL;DR

This paper details the experimental techniques used to produce a chromium Bose-Einstein condensate, highlighting adaptations needed due to its large magnetic dipole moment and discussing the properties of the resulting quantum gas.

Contribution

It introduces specialized cooling and trapping methods for chromium BECs, enabling the production of pure condensates with up to 10^5 atoms and analyzing their trapping parameters.

Findings

Successful creation of a chromium BEC with up to 10^5 atoms

Adapted cooling and trapping techniques for large dipolar gases

Insights into the properties of a degenerate chromium quantum gas

Abstract

The recent achievement of Bose-Einstein condensation of chromium atoms [1] has opened longed-for experimental access to a degenerate quantum gas with long-range and anisotropic interaction. Due to the large magnetic moment of chromium atoms of 6 {$\mu$}B, in contrast to other Bose- Einstein condensates (BECs), magnetic dipole-dipole interaction plays an important role in a chromium BEC. Many new physical properties of degenerate gases arising from these magnetic forces have been predicted in the past and can now be studied experimentally. Besides these phenomena, the large dipole moment leads to a breakdown of standard methods for the creation of a chromium BEC. Cooling and trapping methods had to be adapted to the special electronic structure of chromium to reach the regime of quantum degeneracy. Some of them apply generally to gases with large dipolar forces. We present here a detailed discussion of the experimental techniques which are used to create a chromium BEC and alow us to produce pure condensates with up to {$10^5$} atoms in an optical dipole trap. We also describe the methods used to determine the trapping parameters.