All optical cooling of $^{39}$K to Bose Einstein condensation

TL;DR

This paper demonstrates an all-optical method to produce Bose-Einstein condensates of $^{39}$K atoms, utilizing gray molasses, optical traps, and Feshbach resonance tuning, achieving rapid BEC production and exploring interaction effects.

Contribution

It introduces a new all-optical approach for creating $^{39}$K BECs with fast cycle times and tunable interactions, advancing experimental control in ultracold atom research.

Findings

Successfully produced BECs with 3×10^5 atoms every 7 seconds.

Studied condensate expansion across 1D to 3D interaction regimes.

Enhanced scattering length near Feshbach resonance improves evaporative cooling.

Abstract

We report the all-optical production of Bose Einstein condensates (BEC) of $^{39}$K atoms. We directly load $3 \times 10^{7}$ atoms in a large volume optical dipole trap from gray molasses on the D1 transition. We then apply a small magnetic quadrupole field to polarize the sample before transferring the atoms in a tightly confining optical trap. Evaporative cooling is finally performed close to a Feshbach resonance to enhance the scattering length. Our setup allows to cross the BEC threshold with $3 \times 10^5$ atoms every 7s. As an illustration of the interest of the tunability of the interactions we study the expansion of Bose-Einstein condensates in the 1D to 3D crossover.